SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for deferred tax asset
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 859	$ 0	$ 0
Charged to Expenses	0	0	0
Adjustments to Valuation Accounts	671	859	0
Deductions	0	0	0
Balance at End of Year	1,530	859	0
Allowance for uncollectible accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	5,720	7,451	5,952
Charged to Expenses	200	0	1,499
Adjustments to Valuation Accounts	0	0	0
Deductions	0	(1,731)	0
Balance at End of Year	5,920	5,720	7,451
Allowance for notes receivable
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	0	0	0
Charged to Expenses	0	0	0
Adjustments to Valuation Accounts	0	0	0
Deductions	0	0	0
Balance at End of Year	$ 0	$ 0	$ 0