Stockholders' Equity (Details 2) (USD $) In Thousands, unless otherwise specified	1 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Stockholders' Equity Note [Abstract]
Aggregate authorized amount	$ 200,000
Shares repurchased		9,157
Aggregate cost of shares repurchased				68,500
Remaining amount for purchases under the repurchase program		$ 105,240	$ 173,697