Consolidated Statements Of Stockholders' Equity (USD $) Share data in Thousands, unless otherwise specified	Common Stock [Member]	Issued Shares [Member]	Capital In Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Balances at Dec. 31, 2008	$ 31,000,000		$ 1,574,000,000	$ 3,390,000,000	$ (175,000,000)	$ (363,000,000)	$ 4,457,000,000
Balances, issued shares at Dec. 31, 2008		187,857
Comprehensive income:
Net income				1,040,000,000			1,040,000,000
Other comprehensive income (loss):
Net unrealized investment gains, net of tax expense					230,000,000		230,000,000
Reclassification adjustment for net realized gains included in net income, net of tax expense					(13,000,000)		(13,000,000)
Common stock repurchases						(23,000,000)	(23,000,000)
Stock-based compensation			66,000,000				66,000,000
Restricted stock grants and restricted stock unit vesting	0						0
Restricted stock grants and restricted stock unit vesting, issued shares		978
Restricted stock forfeitures	0		0				0
Restricted stock forfeitures, issued shares		(87)
Stock option exercises	1,000,000	1,053,000	18,000,000				19,000,000
Stock option and restricted stock tax benefit			0				0
Balances at Dec. 31, 2009	32,000,000		1,658,000,000	4,430,000,000	42,000,000	(386,000,000)	5,776,000,000
Balances, issued shares at Dec. 31, 2009		189,801
Comprehensive income:
Net income				1,099,000,000			1,099,000,000
Other comprehensive income (loss):
Net unrealized investment gains, net of tax expense					82,000,000		82,000,000
Reclassification adjustment for net realized gains included in net income, net of tax expense					(4,000,000)		(4,000,000)
Common stock repurchases						(108,000,000)	(108,000,000)
Stock-based compensation			63,000,000				63,000,000
Restricted stock grants and restricted stock unit vesting	0						0
Restricted stock grants and restricted stock unit vesting, issued shares		5
Restricted stock forfeitures	0		0				0
Restricted stock forfeitures, issued shares		(127)
Stock option exercises	0		17,000,000				17,000,000
Stock option exercises, issued shares		566
Stock option and restricted stock tax benefit			(1,000,000)				(1,000,000)
Balances at Dec. 31, 2010	32,000,000		1,737,000,000	5,529,000,000	120,000,000	(494,000,000)	6,924,000,000
Balances, issued shares at Dec. 31, 2010		190,245
Comprehensive income:
Net income				1,419,000,000			1,419,000,000
Other comprehensive income (loss):
Net unrealized investment gains, net of tax expense					190,000,000		190,000,000
Reclassification adjustment for net realized gains included in net income, net of tax expense					(7,000,000)		(7,000,000)
Common stock repurchases						(541,000,000)	(541,000,000)
Dividends declared			0	(123,000,000)			(123,000,000)
Stock-based compensation			67,000,000				67,000,000
Restricted stock grants and restricted stock unit vesting	0						0
Restricted stock grants and restricted stock unit vesting, issued shares		11
Restricted stock forfeitures	0		0				0
Restricted stock forfeitures, issued shares		(105)
Stock option exercises	0		134,000,000				134,000,000
Stock option exercises, issued shares		3,079					3,079
Stock option and restricted stock tax benefit			0				0
Balances at Dec. 31, 2011	$ 32,000,000		$ 1,938,000,000	$ 6,825,000,000	$ 303,000,000	$ (1,035,000,000)	$ 8,063,000,000
Balances, issued shares at Dec. 31, 2011		193,230