Income Taxes - Tax Effects of Cumulative Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets:
Accrued expenses	$ 1,976	$ 2,994
Allowance Accounts	2,960	4,861
Net operating loss carryforward	87,705	98,896
Capital loss carryforward	0	1,114
Equity method investment	35,292	58,820
Original issue discount	9,624	17,924
Basis in identified intangibles	9,408	15,286
Tax credit carryforwards	6,929	7,051
Contingency accrual	788	0
Other	4,035	10,755
Total non-current deferred income tax asset	158,717	217,701
Valuation allowance	(153,463)	(217,589)
Net non-current deferred income tax asset	5,254	112
Deferred income tax liabilities:
Other	0	(1,240)
Unbilled receivables	(3,501)	(1,908)
Basis in property, plant and equipment	0	(531)
Total net non-current deferred income tax asset (liability)	$ 1,753	0
Total net non-current deferred income tax asset (liability)		$ (3,567)