Consolidated Statement of Stockholders' Equity (Unaudited) - 3 months ended Mar. 31, 2017 - USD ($) $ in Thousands		Total	Common stocks	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income, net of tax
Balance, beginning of year at Dec. 31, 2016		$ 941,884	$ 25	$ 216,482	$ 616,322	$ 109,055
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares repurchased			0	(5,749)
Shares issued for stock-based awards			0	1,244
Compensation expense and related tax benefit for stock-based award grants				1,044
Net income		19,936			19,936
Dividends on common stock ($0.25 per share)					(6,367)
Change in net unrealized investment appreciation	[1]					7,515
Change in liability for underfunded employee benefit plans	[2]					878
All other changes in stockholders’ equity accounts		(1,435)
Balance, end of period at Mar. 31, 2017		$ 960,385	$ 25	$ 213,021	$ 629,891	$ 117,448

[1] The change in net unrealized appreciation is net of reclassification adjustments and income taxes.

[2] The change in liability for underfunded employee benefit plans is net of reclassification adjustments and income taxes.