Summary of Significant Accounting Policies - Allowance for Credit Losses and Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Management Fees and Other Revenues
Insurance reserve for insurance subsidiaries and other self-insurance programs	$ 82,500	$ 81,800
Allowance for Credit Losses
Balance, beginning of period	23,460	22,498	$ 30,094
Provision for credit losses	12,631	11,304	7,319
Accounts written off, net of recoveries	(9,271)	(10,342)	(14,915)
Balance, end of period	26,820	23,460	$ 22,498
Income Taxes
Provision for federal income taxes for REIT entities	0
Deferred tax liabilities, net	$ 278,300	$ 301,700