Equity Textuals (Details) - USD ($) $ / shares in Units, $ in Thousands	2 Months Ended	12 Months Ended
	Feb. 13, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Purchase of noncontrolling interest		$ 4,580	$ 1,961	$ 2,075
Preferred Stock, Shares Authorized		1,000,000
Common stock, shares authorized		500,000,000	500,000,000
Common stock, shares, issued		191,935,647	195,403,644
Common stock, shares outstanding		186,614,747	189,405,244
Treasury Stock, Shares, Acquired	429,859	6,210,606	8,811,847
Treasury Stock, Value, Acquired, Par Value Method	$ 16,700	$ 199,600	$ 227,900
Treasury Stock Acquired, Average Cost Per Share	$ 38.83	$ 32.14	$ 25.87
Stock Repurchase Program, Authorized Amount		$ 400,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 168,600
Dividends declared per share	$ 0.17	$ 0.58	$ 0.51	$ 0.44
Payments of Dividends, Common Stock		$ 108,750	$ 98,418	$ 87,570