Schedule II Valuation and Qualifying Accounts (Details) - Reserve for Uncollectible Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Movement in Reserve [Roll Forward]
Balance at beginning of year	$ 305,000	$ 305,000
Additions - charged to cost and expenses	258,542	250,884
Additions - recoveries	51,900	57,633
Deductions	310,442	308,517
Balance at end of year	$ 305,000	$ 305,000