Consolidated Statement of Stockholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified		Total	Common Stocks [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income, Net of Tax [Member]
Balance, beginning of year at Dec. 31, 2011		$ 696,141	$ 25	$ 213,045	$ 400,485	$ 82,586
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense and related tax benefit for stock-based award grants				1,229
Shares repurchased (137,792 shares)			(1)	(2,899)
Shares issued for stock-based awards (49,832 shares)			1	906
Net income (loss)		42,630			42,630
Dividends on common stock ($0.45 per share)					(11,455)
Change in net unrealized investment appreciation	[1]					24,954
Change in liability for underfunded employee benefit plans						2,316
All other changes in stockholders’ equity accounts		15,051
Balance, end of year at Sep. 30, 2012		$ 753,822	$ 25	$ 212,281	$ 431,660	$ 109,856

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