Basis and Summary of Significant Accounting Policies - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Accounts Payable	$ 90,409	$ 71,941
Accrued Insurance Costs	49,306	47,649
Accrued Salaries and Benefits	49,696	41,612
Accrued Real Estate and Sales Taxes	31,763	32,986
Deferred Rent	30,472	31,859
Other Accrued Expenses and Liabilities	74,380	71,719
Accounts Payable and Accrued Expenses	$ 326,026	$ 297,766