Shareholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 25, 2013	Feb. 28, 2011
Stockholders Equity Note [Line Items]
Common stock authorized to be repurchased, number of shares					25,000,000	20,000,000
Common stock repurchased, value		$ 162,078	$ 214,195	$ 160,669
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	19,012,000	19,012,000
Common stock dividends, paid per share	$ 0.09		$ 0.07	$ 0.06
Common stock dividends, total cash paid		51,404	42,450	38,037
Payments of Ordinary Dividends, Common Stock		51,404	42,450	38,037
Common Stock and Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Common stock repurchased, shares		5,988,000	10,466,000	6,135,000
Common stock repurchased, value		162,078	214,195	160,669
Retained Earnings
Stockholders Equity Note [Line Items]
Common stock dividends, total cash paid		$ 51,404	$ 42,450	$ 38,037