Schedule II - Valuation And Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation And Qualifying Accounts [Abstract]
Balance at beginning of period	$ 6,048	$ 3,906	$ 3,908
Additions charged to costs and expenses	106,216	70,608	48,098
Deductions	(104,148)	(68,466)	(48,100)
Balance at end of period	$ 8,116	$ 6,048	$ 3,906