SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - Allowance for uncollectible Accounts - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 218,399	$ 238,897	$ 251,734
Acquisitions	0	0	0
Amounts charged to income	42,287	478,365	442,985
Amounts written off	207,762	498,863	455,822
Balance at end of year	$ 52,924	$ 218,399	$ 238,897