Condensed Consolidating Financial Information (Statements of Cash Flows) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$ 97,636	$ 144,479	$ 107,376
Cash flows from investing activities:
Sale of investment securities	116,070	270,576	154,615
Maturities of investment securities	10,822	5,491	930
Purchase of investment securities	(117,211)	(214,146)	(305,731)
Proceeds from sale or liquidation of long-term investments	4,552	1,303	2,416
Purchase of long-term investments	(50)	(10,000)	(12,000)
Investments in real estate ventures	(44,107)	(70,272)	(40,916)
Distributions from real estate ventures	33,204	17,563	7,309
Increase in cash surrender value of life insurance policies	(484)	(1,742)	(484)
Decrease (increase) in restricted assets	10,181	(6,889)	(872)
Issuance of notes receivable	0	(4,410)	(8,250)
Investments in subsidiaries	0	0	0
Proceeds from sale of fixed assets	45	4	4
Purchase of subsidiaries	(250)	0	(750)
Repayment of notes receivable	4,410	4,000	4,850
Purchase of preferred securities	0	0	(1,000)
Capital expenditures	(26,691)	(10,977)	(23,404)
Proceeds from sale of preferred securities	0	1,000	0
Investments in real estate held for sale	(245)	(12,603)	0
Pay down of investment securities	9,212	8,739	1,849
Net cash used in investing activities	(542)	(22,363)	(221,434)
Cash flows from financing activities:
Proceeds from issuance of debt	243,620	2,105	413,914
Deferred financing costs	(6,600)	(624)	(12,360)
Repayments of debt	(5,365)	(6,684)	(12,601)
Borrowings under revolver	144,294	153,361	886,130
Repayments on revolver	(110,614)	(167,915)	(898,788)
Capital contributions received	0	0	0
Intercompany dividends paid	0	0	0
Dividends and distributions on common stock	(198,947)	(188,151)	(167,328)
Distributions to non-controlling interest	(11,545)	(3,280)	(9,339)
Contributions from non-controlling interest	248	813	0
Proceeds from exercise of Vector options	398	1,441	5,151
Tax benefit of options exercised	579	821	1,178
Net cash provided by (used in) financing activities	56,068	(208,113)	205,957
Net increase (decrease) in cash and cash equivalents	153,162	(85,997)	91,899
Cash and cash equivalents, beginning of year	240,368	326,365	234,466
Cash and cash equivalents, end of year	393,530	240,368	326,365
Consolidating Adjustments
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	(211,386)	(209,671)	(100,730)
Cash flows from investing activities:
Sale of investment securities	0	0	0
Maturities of investment securities	0	0	0
Purchase of investment securities	0	0	0
Proceeds from sale or liquidation of long-term investments	0	0	0
Purchase of long-term investments	0	0	0
Investments in real estate ventures	0	0	0
Distributions from real estate ventures	0	0	0
Increase in cash surrender value of life insurance policies	0	0	0
Decrease (increase) in restricted assets	0	0	0
Issuance of notes receivable		0	35,000
Investments in subsidiaries	19,219	103,174	85,278
Proceeds from sale of fixed assets	0	0	0
Purchase of subsidiaries	0		0
Repayment of notes receivable	0	0	(35,000)
Purchase of preferred securities			0
Capital expenditures	0	0	0
Investments in real estate held for sale	0	0
Pay down of investment securities	0	0	0
Net cash used in investing activities	19,219	103,174	85,278
Cash flows from financing activities:
Proceeds from issuance of debt	0	0	(35,000)
Deferred financing costs	0	0	0
Repayments of debt	0	0	35,000
Borrowings under revolver	0	0	0
Repayments on revolver	0	0	0
Capital contributions received	(19,219)	(103,174)	(85,278)
Intercompany dividends paid	211,386	211,168	100,730
Dividends and distributions on common stock	0	0	0
Distributions to non-controlling interest	0	0	0
Contributions from non-controlling interest	0	0
Proceeds from exercise of Vector options	0	0	0
Tax benefit of options exercised	0	(1,497)	0
Net cash provided by (used in) financing activities	192,167	106,497	15,452
Net increase (decrease) in cash and cash equivalents	0	0	0
Cash and cash equivalents, beginning of year	0	0	0
Cash and cash equivalents, end of year	0	0	0
Parent/Issuer
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	135,820	136,370	61,779
Cash flows from investing activities:
Sale of investment securities	105,815	256,161	154,615
Maturities of investment securities	10,822	5,491	930
Purchase of investment securities	(117,211)	(207,822)	(299,417)
Proceeds from sale or liquidation of long-term investments	4,552	1,106	2,367
Purchase of long-term investments	0	(10,000)	(12,000)
Investments in real estate ventures	0	0	0
Distributions from real estate ventures	0	0	0
Increase in cash surrender value of life insurance policies	0	(1,257)	0
Decrease (increase) in restricted assets	(15)	(6)	188
Issuance of notes receivable		0	(35,000)
Investments in subsidiaries	(19,219)	(103,174)	(85,278)
Proceeds from sale of fixed assets	0	0	0
Purchase of subsidiaries	0		0
Repayment of notes receivable	0	0	35,000
Purchase of preferred securities			0
Capital expenditures	(86)	0	(15)
Proceeds from sale of preferred securities		0
Investments in real estate held for sale	0	0
Pay down of investment securities	9,212	8,739	1,849
Net cash used in investing activities	(6,130)	(50,762)	(236,761)
Cash flows from financing activities:
Proceeds from issuance of debt	243,225	0	408,750
Deferred financing costs	(6,600)	0	(12,360)
Repayments of debt	0	0	0
Borrowings under revolver	0	0	0
Repayments on revolver	0	0	0
Capital contributions received	0	0	0
Intercompany dividends paid	0	0	0
Dividends and distributions on common stock	(198,947)	(188,151)	(167,328)
Distributions to non-controlling interest	0	0	0
Contributions from non-controlling interest	0	0
Proceeds from exercise of Vector options	398	1,441	5,151
Tax benefit of options exercised	579	821	1,178
Net cash provided by (used in) financing activities	38,655	(185,889)	235,391
Net increase (decrease) in cash and cash equivalents	168,345	(100,281)	60,409
Cash and cash equivalents, beginning of year	111,470	211,751	151,342
Cash and cash equivalents, end of year	279,815	111,470	211,751
Subsidiary Guarantors
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	112,562	172,065	83,671
Cash flows from investing activities:
Sale of investment securities	10,255	14,415	0
Maturities of investment securities	0	0	0
Purchase of investment securities	0	(6,324)	(6,314)
Proceeds from sale or liquidation of long-term investments	0	0	0
Purchase of long-term investments	0	0	0
Investments in real estate ventures	0	0	0
Distributions from real estate ventures	0	0	0
Increase in cash surrender value of life insurance policies	(484)	(485)	(484)
Decrease (increase) in restricted assets	9,696	(6,883)	(371)
Issuance of notes receivable		0	0
Investments in subsidiaries	0	0	0
Proceeds from sale of fixed assets	32	4	4
Purchase of subsidiaries	0		0
Repayment of notes receivable	0	0	0
Purchase of preferred securities			0
Capital expenditures	(6,445)	(3,730)	(16,466)
Proceeds from sale of preferred securities		0
Investments in real estate held for sale	0	0
Pay down of investment securities	0	0	0
Net cash used in investing activities	13,054	(3,003)	(23,631)
Cash flows from financing activities:
Proceeds from issuance of debt	0	1,799	40,164
Deferred financing costs	0	(624)	0
Repayments of debt	(5,226)	(6,362)	(43,724)
Borrowings under revolver	144,294	153,361	886,130
Repayments on revolver	(110,614)	(167,915)	(898,788)
Capital contributions received	2,800	33,658	15,270
Intercompany dividends paid	(154,447)	(181,825)	(61,180)
Dividends and distributions on common stock	0	0	0
Distributions to non-controlling interest	0	0	0
Contributions from non-controlling interest	0	0
Proceeds from exercise of Vector options	0	0	0
Tax benefit of options exercised	0	1,497	0
Net cash provided by (used in) financing activities	(123,193)	(166,411)	(62,128)
Net increase (decrease) in cash and cash equivalents	2,423	2,651	(2,088)
Cash and cash equivalents, beginning of year	12,375	9,724	11,812
Cash and cash equivalents, end of year	14,798	12,375	9,724
Subsidiary Non-Guarantors
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	60,640	45,715	62,656
Cash flows from investing activities:
Sale of investment securities	0	0	0
Maturities of investment securities	0	0	0
Purchase of investment securities	0	0	0
Proceeds from sale or liquidation of long-term investments	0	197	49
Purchase of long-term investments	(50)	0	0
Investments in real estate ventures	(44,107)	(70,272)	(40,916)
Distributions from real estate ventures	33,204	17,563	7,309
Increase in cash surrender value of life insurance policies	0	0	0
Decrease (increase) in restricted assets	500	0	(689)
Issuance of notes receivable		(4,410)	(8,250)
Investments in subsidiaries	0	0	0
Proceeds from sale of fixed assets	13	0	0
Purchase of subsidiaries	(250)		(750)
Repayment of notes receivable	4,410	4,000	4,850
Purchase of preferred securities			(1,000)
Capital expenditures	(20,160)	(7,247)	(6,923)
Proceeds from sale of preferred securities		1,000
Investments in real estate held for sale	(245)	(12,603)
Pay down of investment securities	0	0	0
Net cash used in investing activities	(26,685)	(71,772)	(46,320)
Cash flows from financing activities:
Proceeds from issuance of debt	395	306	0
Deferred financing costs	0	0	0
Repayments of debt	(139)	(322)	(3,877)
Borrowings under revolver	0	0	0
Repayments on revolver	0	0	0
Capital contributions received	16,419	69,516	70,008
Intercompany dividends paid	(56,939)	(29,343)	(39,550)
Dividends and distributions on common stock	0	0	0
Distributions to non-controlling interest	(11,545)	(3,280)	(9,339)
Contributions from non-controlling interest	248	813
Proceeds from exercise of Vector options	0	0	0
Tax benefit of options exercised	0	0	0
Net cash provided by (used in) financing activities	(51,561)	37,690	17,242
Net increase (decrease) in cash and cash equivalents	(17,606)	11,633	33,578
Cash and cash equivalents, beginning of year	116,523	104,890	71,312
Cash and cash equivalents, end of year	$ 98,917	$ 116,523	$ 104,890