Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2018	Apr. 01, 2018	Sep. 30, 2018	Dec. 31, 2017
Income Taxes Tax Cuts And Jobs Act [Abstract]
Increase (decrease) to provisional tax expense, net	$ (17,336)	$ 47,800
Tax cuts and jobs act, Date enacted			Dec. 22, 2017
Non-US local country withholding taxes, Tax Cuts and Jobs Act of 2017				$ 1,657
US state and local taxes, Tax Cuts and Jobs Act of 2017	$ 2,412