SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - Allowance for uncollectible Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 8,328	$ 52,924	$ 218,399
Acquisitions	0	0	0
Amounts charged to income	13,458	21,715	42,287
Amounts written off	21,786	66,311	207,762
Balance at end of year	$ 0	$ 8,328	$ 52,924