Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Deposits in trusts for employee deferred compensation plans	$ 236,371	$ 198,256
Other	84,434	70,524
Other current assets	$ 320,805	$ 268,780