Basis and Summary of Significant Accounting Policies - Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Accounts Payable	$ 71,751	$ 88,369
Accrued Insurance Costs	39,181	40,423
Accrued Salaries and Benefits	45,832	40,790
Accrued Real Estate and Sales Taxes	30,749	30,332
Deferred Rent		27,270
Other Accrued Expenses and Liabilities	59,266	65,969
Accounts Payable and Accrued Expenses	$ 246,779	$ 293,153