Stockholders' Equity (Details) (USD $)	1 Months Ended	9 Months Ended
	Aug. 31, 2004	Dec. 31, 2012
Summary of Repurchase Program Activity
Stock repurchase program, Authorized amount	$ 200,000,000	$ 300,000,000
Total repurchases, Aggregate Price		284,128,000
Available for repurchase, Aggregate Price		15,872,000
Stock repurchase program, Number of shares authorized		0
Total repurchases, Repurchased Shares		27,273,000
Total repurchases, Average Price Per Share (USD per share)	$ 10.04	$ 0
Open market repurchases [Member]
Summary of Repurchase Program Activity
Total repurchases, Aggregate Price		173,611,000
Total repurchases, Repurchased Shares		17,284,000
Total repurchases, Average Price Per Share (USD per share)		$ 0
Structured stock repurchase agreements [Member]
Summary of Repurchase Program Activity
Total repurchases, Aggregate Price		$ 110,517,000	[1]
Total repurchases, Repurchased Shares		9,989,000	[1]
Total repurchases, Average Price Per Share (USD per share)		$ 0	[1]

[1] The amounts above do not include gains recorded to additional paid-in-capital of $12.8 million from structured stock repurchase agreements which settled in cash. The average price per share for structured stock repurchase agreements adjusted for gains from settlements in cash would have been $9.78 per share and for total repurchases would have been $9.97 per share.