Stockholders' Equity - Narrative (Details) (USD $)	1 Months Ended		3 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Mar. 31, 2014	Mar. 31, 2013
Equity [Abstract]
Dividends declared per common share	$ 0.75		$ 0.75	$ 0.75
Payments of Dividends			$ 14,293,000	$ 14,512,000
Stock Repurchase Program, Authorized Amount		100,000,000
Stock Repurchased During Period, Shares			178,528
Stock Repurchased During Period, Value			15,000,000
Cumulative Amount of Shares Repurchased			590,550
Cumulative Payments for Repurchase of Common Stock			44,700,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount			55,300,000
Treasury Stock Reissued (shares)			307,556
Treasury Stock Reissued			$ 11,100,000