Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 44,829	$ 55,148	$ 49,284
Additions	6,681	0	5,864
Deductions	0	(10,319)	0
Balance at End of Year	51,510	44,829	55,148
Allowance for doubtful accounts-note receivable
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	0	376	363
Additions		0	13
Deductions		(376)	0
Balance at End of Year		0	376
Tax valuation allowances
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	44,829	54,772	48,921
Additions	6,681	0	5,851
Deductions	0	(9,943)	0
Balance at End of Year	$ 51,510	$ 44,829	$ 54,772