Income Taxes - The components of the net deferred income tax asset (liability) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Depreciation and amortization	$ 9,297	$ 8,288
Deferred revenue	655	716
Net operating loss carryforwards	71,330	67,148
Alternative minimum tax credit carryforward	2,523	2,527
Research and development tax credit carryforward	566	1,133
Accrued expenses and other	8,211	8,153
Total deferred tax assets	92,582	87,965
Deferred tax liabilities:
Depreciation and amortization	(4,186)	(7,870)
Intangible assets	(1,854)	(3,276)
Deferred expenses and other	(127)	(409)
Total deferred tax liabilities	(6,167)	(11,555)
Valuation allowance:
Beginning balance	0	0
Increase during the period	(88,737)	0
Total valuation allowance	(88,737)	0
Net deferred tax asset (liability)	(2,322)	76,410
Deferred income tax asset	39	81,744
Deferred income tax liability	$ (2,361)	$ (5,334)