Schedule II - Valuation and Qualifying Accounts (Details) - Provision for Uncollectible Accounts [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period		$ 7,910	$ 5,854	$ 5,924
Charged to Costs and Expenses		14,730	9,519	4,245
Charged to Other Accounts	[1]	(79)	(102)	(41)
Deductions	[2]	12,309	7,361	4,274
Ending Balance		$ 10,252	$ 7,910	$ 5,854

[1] Recoveries of accounts previously written off and minor adjustments.

[2] Uncollectible accounts written off.