Schedule II - Valuation and Qualifying Accounts - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
Balance at beginning of period	[1]	$ 17,066	$ 24,175	$ 31,820
Charged to expenses	[1]	9,254	6,641	7,982
Adjustments to valuation accounts	[1]
Deductions	[1]	(5,882)	(13,750)	(15,627)
Balance at end of period	[1]	20,438	17,066	24,175
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
Balance at beginning of period		54,155	95,126	27,905
Charged to expenses
Adjustments to valuation accounts		(8,742)	(40,971)	67,221
Deductions
Balance at end of period		$ 45,413	$ 54,155	$ 95,126

[1] Includes allowances on accounts receivable and straight-line rents.