Income Tax (Pre-tax Income Foreign and Domestic) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income (Loss) from Continuing Operations before Income Taxes, Domestic									$ 870,532	$ 758,496	$ 493,328
Income (Loss) from Continuing Operations before Income Taxes, Foreign									272,283	285,450	251,467
Income before income taxes	$ 255,494	$ 340,162	$ 339,315	$ 207,844	$ 295,543	$ 287,600	$ 353,223	$ 107,580	$ 1,142,815	$ 1,043,946	$ 744,795