General Insurance Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selling, General and Administrative Expense [Abstract]
Compensation	$ 625,364	$ 564,008	$ 406,601
Commissions	222,028	206,360	210,797
Other	333,835	308,628	163,593
Total general insurance expenses	$ 1,181,227	$ 1,078,996	$ 780,991