Consolidated Statements of Changes in Stockholder's Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock		Preferred Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest
Balance at Dec. 31, 2010	$ 1,044,726	$ 125,687	[1]	$ 3,000	$ 864,303	$ 51,644	$ 92
Comprehensive Income
Net income	61,270				61,290		(20)
Change in net unrealized investment gains/losses	74,900					74,900
Non-credit impairment losses	(6,498)					(6,498)
Change in underfunded status of other postretirement benefit plans	(5)					(5)
Total comprehensive income	129,667
Stock-based compensation, including the net issuance of common shares under compensation plans	7,940	7,940	[1]
Dividends on preferred stock	(75)				(75)
Dividends on common stock	(3,812)				(3,812)
Balance at Jun. 30, 2011	1,178,447	133,627	[1]	3,000	921,706	120,041	73
Balance at Dec. 31, 2011	1,202,429	137,206	[1]	3,000	884,263	177,845	115
Comprehensive Income
Net income	36,760				36,878		(118)
Change in net unrealized investment gains/losses	61,717					61,717
Non-credit impairment losses	(6,356)					(6,356)
Change in underfunded status of other postretirement benefit plans	(96)					(96)
Total comprehensive income	92,025
Stock-based compensation, including the net issuance of common shares under compensation plans	6,627	6,627	[1]
Purchase of 4,102,596 shares of common stock	(136,466)	(18,251)	[1]		(118,215)
Dividends on preferred stock	(75)				(75)
Dividends on common stock	(5,751)				(5,751)
Receipts related to noncontrolling interest	1						1
Balance at Jun. 30, 2012	$ 1,158,789	$ 125,582	[1]	$ 3,000	$ 797,100	$ 233,110	$ (3)

[1] All activity for the periods shown relates to Class A Common Stock