Equity Textuals (Details) - USD ($) $ / shares in Units, $ in Thousands	2 Months Ended	3 Months Ended	12 Months Ended
	Feb. 19, 2019	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Purchase of noncontrolling interest			$ 0	$ 4,580	$ 1,961
Preferred Stock, Shares Authorized			1,000,000
Preferred Stock, Par or Stated Value Per Share			$ 1
Common stock, shares authorized			500,000,000	500,000,000
Common stock, par or stated value per share			$ 1	$ 1
Common stock, shares, issued			184,720,582	191,935,647
Common stock, shares outstanding			181,470,582	186,614,747
Treasury Stock, Shares, Acquired			7,347,838	6,210,606
Treasury Stock, Value, Acquired, Par Value Method			$ 277,600	$ 199,600
Treasury Stock Acquired, Average Cost Per Share			$ 37.78	$ 32.14
Stock Repurchase Program, Authorized Amount			$ 400,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount			$ 192,500
Dividends declared per share		$ 0.51	$ 0.68	$ 0.58
Payments of Dividends, Common Stock			$ 123,849	$ 108,750	$ 98,418
Business Acquisition, Percentage of Voting Interests Acquired				22.00%
Subsequent Event [Member]
Treasury Stock, Shares, Acquired	193,395
Treasury Stock, Value, Acquired, Par Value Method	$ 7,900
Treasury Stock Acquired, Average Cost Per Share	$ 40.70