Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 7,976	$ 6,567	$ 6,886
Charged to costs and expenses	0	3,155	2,143
Deductions	(7,976)	(1,746)	(2,462)
Balance at end of year	0	7,976	6,567
Tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	10,578	12,347	21,175
Charged to costs and expenses	4	(1,769)	(8,828)
Deductions	0	0	0
Balance at end of year	$ 10,582	$ 10,578	$ 12,347