SEC Schedule II Valuation and Qualifying Accounts (Details) - Allowance For Doubtful Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 21,209	$ 24,719	$ 28,675
Additions Charged Against Operations	(99)	3,076	9,326
Uncollectable Accounts Written-Off	(6,451)	(6,586)	(13,282)
Balance at End of Year	$ 14,659	$ 21,209	$ 24,719