FAIR VALUE OF FINANCIAL INSTRUMENTS (Financial Instruments Measured at Fair Value) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2015 USD ($) security	Dec. 31, 2014 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	$ 3,061,208	$ 3,088,922
Trading Securities	$ 16,975	20,928
Number of securities transferred between Level 1 and 2 \| security	0
Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	$ 2,824,961	2,843,079
U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	21,649	25,972
U.S. Government Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	233,030	351,672
General Obligations [Member] \| Midwest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	165,456	185,920
General Obligations [Member] \| Northeast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	58,445	61,154
General Obligations [Member] \| South [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	128,789	126,220
General Obligations [Member] \| West [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	106,814	78,433
Special Revenue [Member] \| Midwest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	157,706	131,402
Special Revenue [Member] \| Northeast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	24,599	12,631
Special Revenue [Member] \| South [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	148,437	111,222
Special Revenue [Member] \| West [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	82,041	71,303
Foreign Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	82,528	140,173
Public Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	215,683	212,357
Corporate Bonds [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	113,119	137,133
Corporate Bonds [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	224,255	215,475
Corporate Bonds [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	174,597	177,001
Corporate Bonds [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	93,509	89,035
Corporate Bonds [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	142,400	134,529
Corporate Bonds [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	263,485	223,582
Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	16,738	17,558
Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	366,015	337,289
Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	5,666	3,018
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	236,247	245,843
Common Stocks [Member] \| Public Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	19,060	20,290
Common Stocks [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	11,211	13,717
Common Stocks [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	44,810	45,459
Common Stocks [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	23,315	23,314
Common Stocks [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	28,217	30,356
Common Stocks [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	13,364	13,995
Common Stocks [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	95,694	93,663
Nonredeemable Preferred Stocks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	576	5,049
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	3,061,208	3,088,922
Trading Securities	16,975	20,928
Short- Term Investments	175	175
Money Market Accounts	20,805	28,095
Corporate-Owned Life Insurance	1,716	918
Total Assets Measured at Fair Value	3,100,879	3,139,038
Recurring [Member] \| Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	2,824,961	2,843,079
Recurring [Member] \| U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	21,649	25,972
Recurring [Member] \| U.S. Government Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	233,030	351,672
Recurring [Member] \| General Obligations [Member] \| Midwest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	165,456	185,920
Recurring [Member] \| General Obligations [Member] \| Northeast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	58,445	61,154
Recurring [Member] \| General Obligations [Member] \| South [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	128,789	126,220
Recurring [Member] \| General Obligations [Member] \| West [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	106,814	78,433
Recurring [Member] \| Special Revenue [Member] \| Midwest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	157,706	131,402
Recurring [Member] \| Special Revenue [Member] \| Northeast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	24,599	12,631
Recurring [Member] \| Special Revenue [Member] \| South [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	148,437	111,222
Recurring [Member] \| Special Revenue [Member] \| West [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	82,041	71,303
Recurring [Member] \| Foreign Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	82,528	140,173
Recurring [Member] \| Public Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	215,683	212,357
Recurring [Member] \| Corporate Bonds [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	113,119	137,133
Recurring [Member] \| Corporate Bonds [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	224,255	215,475
Trading Securities	3,558	3,352
Recurring [Member] \| Corporate Bonds [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	174,597	177,001
Trading Securities	118
Recurring [Member] \| Corporate Bonds [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	93,509	89,035
Trading Securities	2,032	2,425
Recurring [Member] \| Corporate Bonds [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	142,400	134,529
Trading Securities	335	338
Recurring [Member] \| Corporate Bonds [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	263,485	223,582
Trading Securities	4,094	5,997
Recurring [Member] \| Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	16,738	17,558
Recurring [Member] \| Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	366,015	337,289
Recurring [Member] \| Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	5,666	3,018
Recurring [Member] \| Redeemable Preferred Stocks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	2,485	4,750
Recurring [Member] \| Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	236,247	245,843
Recurring [Member] \| Equity Securities [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	267	411
Recurring [Member] \| Equity Securities [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	986
Recurring [Member] \| Equity Securities [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	942	1,034
Recurring [Member] \| Equity Securities [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	304	327
Recurring [Member] \| Equity Securities [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		411
Recurring [Member] \| Equity Securities [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	229
Recurring [Member] \| Common Stocks [Member] \| Public Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	19,060	20,290
Recurring [Member] \| Common Stocks [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	11,211	13,717
Recurring [Member] \| Common Stocks [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	44,810	45,459
Recurring [Member] \| Common Stocks [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	23,315	23,314
Recurring [Member] \| Common Stocks [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	28,217	30,356
Recurring [Member] \| Common Stocks [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	13,364	13,995
Recurring [Member] \| Common Stocks [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	95,694	93,663
Recurring [Member] \| Nonredeemable Preferred Stocks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	576	5,049
Trading Securities	1,625	1,883
Recurring [Member] \| Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	232,141	237,407
Trading Securities	6,838	8,816
Short- Term Investments	175	175
Money Market Accounts	20,805	28,095
Corporate-Owned Life Insurance	0	0
Total Assets Measured at Fair Value	259,959	274,493
Recurring [Member] \| Level 1 [Member] \| Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| U.S. Government Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| General Obligations [Member] \| Midwest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| General Obligations [Member] \| Northeast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| General Obligations [Member] \| South [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| General Obligations [Member] \| West [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Special Revenue [Member] \| Midwest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Special Revenue [Member] \| Northeast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Special Revenue [Member] \| South [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Special Revenue [Member] \| West [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Foreign Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Public Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Corporate Bonds [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Corporate Bonds [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Trading Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Corporate Bonds [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Trading Securities	0
Recurring [Member] \| Level 1 [Member] \| Corporate Bonds [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Trading Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Corporate Bonds [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Trading Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Corporate Bonds [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Trading Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 1 [Member] \| Redeemable Preferred Stocks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	2,485	4,750
Recurring [Member] \| Level 1 [Member] \| Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	232,141	237,407
Recurring [Member] \| Level 1 [Member] \| Equity Securities [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	267	411
Recurring [Member] \| Level 1 [Member] \| Equity Securities [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	986
Recurring [Member] \| Level 1 [Member] \| Equity Securities [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	942	1,034
Recurring [Member] \| Level 1 [Member] \| Equity Securities [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	304	327
Recurring [Member] \| Level 1 [Member] \| Equity Securities [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities		411
Recurring [Member] \| Level 1 [Member] \| Equity Securities [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	229
Recurring [Member] \| Level 1 [Member] \| Common Stocks [Member] \| Public Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	19,060	20,290
Recurring [Member] \| Level 1 [Member] \| Common Stocks [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	11,211	13,717
Recurring [Member] \| Level 1 [Member] \| Common Stocks [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	44,810	45,458
Recurring [Member] \| Level 1 [Member] \| Common Stocks [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	23,315	23,314
Recurring [Member] \| Level 1 [Member] \| Common Stocks [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	28,217	30,356
Recurring [Member] \| Level 1 [Member] \| Common Stocks [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	13,364	13,995
Recurring [Member] \| Level 1 [Member] \| Common Stocks [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	91,588	89,719
Recurring [Member] \| Level 1 [Member] \| Nonredeemable Preferred Stocks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	576	558
Trading Securities	1,625	1,883
Recurring [Member] \| Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	2,812,815	2,833,200
Trading Securities	10,137	12,112
Short- Term Investments	0	0
Money Market Accounts	0	0
Corporate-Owned Life Insurance	1,716	918
Total Assets Measured at Fair Value	2,824,668	2,846,230
Recurring [Member] \| Level 2 [Member] \| Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	2,812,687	2,828,636
Recurring [Member] \| Level 2 [Member] \| U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	21,649	25,972
Recurring [Member] \| Level 2 [Member] \| U.S. Government Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	233,030	351,672
Recurring [Member] \| Level 2 [Member] \| General Obligations [Member] \| Midwest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	165,456	185,920
Recurring [Member] \| Level 2 [Member] \| General Obligations [Member] \| Northeast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	58,445	61,154
Recurring [Member] \| Level 2 [Member] \| General Obligations [Member] \| South [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	128,789	126,220
Recurring [Member] \| Level 2 [Member] \| General Obligations [Member] \| West [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	106,814	78,433
Recurring [Member] \| Level 2 [Member] \| Special Revenue [Member] \| Midwest [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	157,363	130,883
Recurring [Member] \| Level 2 [Member] \| Special Revenue [Member] \| Northeast [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	24,599	12,631
Recurring [Member] \| Level 2 [Member] \| Special Revenue [Member] \| South [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	148,437	111,222
Recurring [Member] \| Level 2 [Member] \| Special Revenue [Member] \| West [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	82,041	71,303
Recurring [Member] \| Level 2 [Member] \| Foreign Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	82,528	140,173
Recurring [Member] \| Level 2 [Member] \| Public Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	215,683	212,357
Recurring [Member] \| Level 2 [Member] \| Corporate Bonds [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	113,119	137,133
Recurring [Member] \| Level 2 [Member] \| Corporate Bonds [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	224,255	215,475
Trading Securities	3,558	3,352
Recurring [Member] \| Level 2 [Member] \| Corporate Bonds [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	173,364	175,682
Trading Securities	118
Recurring [Member] \| Level 2 [Member] \| Corporate Bonds [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	93,509	89,035
Trading Securities	2,032	2,425
Recurring [Member] \| Level 2 [Member] \| Corporate Bonds [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	142,400	134,529
Trading Securities	335	338
Recurring [Member] \| Level 2 [Member] \| Corporate Bonds [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	253,823	212,589
Trading Securities	4,094	5,997
Recurring [Member] \| Level 2 [Member] \| Mortgage-Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	16,738	17,558
Recurring [Member] \| Level 2 [Member] \| Collateralized Mortgage Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	366,015	337,289
Recurring [Member] \| Level 2 [Member] \| Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	4,630	1,406
Recurring [Member] \| Level 2 [Member] \| Redeemable Preferred Stocks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	0	0
Recurring [Member] \| Level 2 [Member] \| Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	128	4,564
Recurring [Member] \| Level 2 [Member] \| Equity Securities [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	0	0
Recurring [Member] \| Level 2 [Member] \| Equity Securities [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	0
Recurring [Member] \| Level 2 [Member] \| Equity Securities [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	0	0
Recurring [Member] \| Level 2 [Member] \| Equity Securities [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	0	$ 0
Recurring [Member] \| Level 2 [Member] \| Equity Securities [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities
Recurring [Member] \| Level 2 [Member] \| Equity Securities [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading Securities	0
Recurring [Member] \| Level 2 [Member] \| Common Stocks [Member] \| Public Utilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	$ 0
Recurring [Member] \| Level 2 [Member] \| Common Stocks [Member] \| Energy [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 2 [Member] \| Common Stocks [Member] \| Industrials [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	1
Recurring [Member] \| Level 2 [Member] \| Common Stocks [Member] \| Consumer Goods and Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 2 [Member] \| Common Stocks [Member] \| Health Care [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 2 [Member] \| Common Stocks [Member] \| Technology, Media and Telecommunications [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 2 [Member] \| Common Stocks [Member] \| Financial Services [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	128	72
Recurring [Member] \| Level 2 [Member] \| Nonredeemable Preferred Stocks [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	4,491
Trading Securities	0	0
Recurring [Member] \| Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	16,252	18,315
Trading Securities	0	0
Short- Term Investments	0	0
Money Market Accounts	0	0
Corporate-Owned Life Insurance	0	0
Total Assets Measured at Fair Value	16,252	18,315
Recurring [Member] \| Level 3 [Member] \| Fixed Maturities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	12,274	14,443
Recurring [Member] \| Level 3 [Member] \| U.S. Treasury [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 3 [Member] \| U.S. Government Agency [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities	0	0
Recurring [Member] \| Level 3 [Member] \| General Obligations [Member] \| Midwest [Member]

FAIR VALUE OF FINANCIAL INSTRUMENTS (Financial Instruments Measured at Fair Value) (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2015

USD ($)

security

Dec. 31, 2014

USD ($)

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Available-for-sale Securities

$ 3,061,208

$ 3,088,922

Trading Securities