Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts
Movement in Valuation Allowances and Reserves
Balance at beginning of year	$ 17,443	$ 14,319	$ 13,506
Additions charged to expense	16,345	9,770	7,426
Deductions	(15,958)	(6,646)	(6,613)
Balance at end of year	17,830	17,443	14,319
Valuation allowance for deferred tax asset
Movement in Valuation Allowances and Reserves
Balance at beginning of year	142,496	178,156	127,095
Additions charged to expense	5,324	3,682	53,782
Deductions	(37,038)	(39,342)	(2,721)
Balance at end of year	$ 110,782	$ 142,496	$ 178,156