Shareholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended						0 Months Ended	1 Months Ended	9 Months Ended	0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Jul. 31, 2014 Minimum	Jul. 31, 2013 Minimum	Jul. 31, 2014 Maximum	Jul. 31, 2013 Maximum	Oct. 31, 2014 Subsequent Event	Jan. 31, 2013 2013 Stock Repurchase Program	Sep. 30, 2014 2013 Stock Repurchase Program	Oct. 31, 2014 2013 Stock Repurchase Program Subsequent Event
Number of shares authorized to be repurchased under the current open-market stock repurchase program								20,000,000
Repurchase of stock program, period								2 years
Number of shares repurchased under the current open-market stock repurchase program							2,900,726		8,527,884
Payments for shares repurchased under the current open-market stock repurchase program (in dollars)									$ 400,801	$ 138,595
Quarterly dividend approved by Board prior to payment, per share (in dollars per share)			$ 0.10	$ 0.0525	$ 0.125	$ 0.10
Dividends declared	101,924	65,101
Dividends paid	$ 101,924	$ 33,472