Allowance Accounts - Summary of Activity in Valuation Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Uncollectible Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of period	$ 4,735	$ 2,234	$ 5,152
Additions	3,275	5,331	2,236
Deductions	(7,660)	(2,830)
Adjustments	0	0	(5,154)
Balance at the end of period	350	4,735	2,234
Deferred Tax Asset Valuation Allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of period	23,076	22,860	16,391
Additions	0	0	0
Deductions	0	0
Adjustments	(21,140)	216	6,469
Balance at the end of period	$ 1,936	$ 23,076	$ 22,860