Equity Textuals (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Feb. 11, 2016	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2014	Oct. 15, 2013	Jun. 03, 2011
Preferred Stock, Shares Authorized		1,000,000	1,000,000
Common stock, shares authorized		500,000,000	500,000,000	500,000,000
Common stock, shares, issued		200,859,676	200,859,676	205,458,331
Common stock, shares outstanding		195,772,876	195,772,876	204,866,770
Treasury Stock, Shares, Acquired	977,396		12,455,281		11,488,332
Treasury Stock, Value, Acquired, Par Value Method	$ 24,000		$ 345,300		$ 242,900
Treasury Stock Acquired, Average Cost Per Share	$ 24.51		$ 27.72		$ 21.14
Stock Repurchase Program, Authorized Amount		$ 400,000	$ 400,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 278,800	$ 278,800
Dividends declared per share	$ 0.12	$ 0.12	$ 0.44	$ 0.34	$ 0.27
Payments of Dividends, Common Stock			$ 87,570	$ 71,517	$ 57,229
Business Acquisition, Percentage of Voting Interests Acquired		24.40%	24.40%			10.00%	20.00%	70.00%
Purchase of noncontrolling interest			$ 2,075	$ 15,000	$ 23,333