CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total		Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss), net of taxes	Treasury stock, at cost
Beginning balance at Dec. 31, 2013			$ 64	$ 407,056	$ 1,000,312	$ 122,214	$ (430,341)
Options exercised, 2016, 142,203 shares; 2015, 85,532 shares; 2014, 435,665 shares			0
Conversion of common stock units, 2016, 15,629 shares; 2015, 8,293 shares; 2014, 10,834 shares			0
Conversion of restricted stock units, 2016, 222,297 shares; 2015, 198,681 shares; 2014, 169,444 shares			0
Options exercised and conversion of common stock units and restricted stock units				13,906
Share-based compensation expense				1,270
Net income	$ 104,243				104,243
Cash dividends, 2016, $1.06 per share; 2015, $1.00 per share; 2014, $0.92 per share					(39,237)
Change in net unrealized investment gains and losses on fixed maturities and equity securities	163,564	[1],[2]				163,564
Change in net funded status of benefit plans	(1,177)	[1]				(1,177)
Acquisition of shares, 2016, 701,410 shares; 2015, 663,092 shares; 2014, 190,876 shares							(5,411)
Ending balance at Dec. 31, 2014	1,336,463		64	422,232	1,065,318	284,601	(435,752)
Options exercised, 2016, 142,203 shares; 2015, 85,532 shares; 2014, 435,665 shares			0
Conversion of common stock units, 2016, 15,629 shares; 2015, 8,293 shares; 2014, 10,834 shares			0
Conversion of restricted stock units, 2016, 222,297 shares; 2015, 198,681 shares; 2014, 169,444 shares			1
Options exercised and conversion of common stock units and restricted stock units				13,605
Share-based compensation expense				6,811
Net income	93,482				93,482
Cash dividends, 2016, $1.06 per share; 2015, $1.00 per share; 2014, $0.92 per share					(42,523)
Change in net unrealized investment gains and losses on fixed maturities and equity securities	(122,387)	[1],[2]				(122,387)
Change in net funded status of benefit plans	1,159	[1]				1,159
Acquisition of shares, 2016, 701,410 shares; 2015, 663,092 shares; 2014, 190,876 shares							(21,950)
Ending balance at Dec. 31, 2015	1,264,661		65	442,648	1,116,277	163,373	(457,702)
Options exercised, 2016, 142,203 shares; 2015, 85,532 shares; 2014, 435,665 shares			0
Conversion of common stock units, 2016, 15,629 shares; 2015, 8,293 shares; 2014, 10,834 shares			0
Conversion of restricted stock units, 2016, 222,297 shares; 2015, 198,681 shares; 2014, 169,444 shares			0
Options exercised and conversion of common stock units and restricted stock units				2,696
Share-based compensation expense				8,135
Net income	83,765				83,765
Cash dividends, 2016, $1.06 per share; 2015, $1.00 per share; 2014, $0.92 per share					(44,310)
Change in net unrealized investment gains and losses on fixed maturities and equity securities	571	[1],[2]				571
Change in net funded status of benefit plans	(23)	[1]				(23)
Acquisition of shares, 2016, 701,410 shares; 2015, 663,092 shares; 2014, 190,876 shares							(21,513)
Ending balance at Dec. 31, 2016	$ 1,293,982		$ 65	$ 453,479	$ 1,155,732	$ 163,921	$ (479,215)

[1] All amounts are net of tax.

[2] The pretax amounts reclassified from accumulated other comprehensive income, $5,176, $11,667 and $10,943, are included in net realized investment gains and losses and the related tax expenses, $1,812, $4,083 and $3,830, are included in income tax expense in the Consolidated Statements of Operations for the years ended December 31, 2016, 2015 and 2014, respectively.