Description of Business, Basis of Presentation and Consolidation and Significant Accounting Policies - Recent Accounting Pronouncements - Adoption of New Accounting Standards (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets:
Unbilled receivable	$ 12,702	$ 16,307
Other non-current assets	11,452	14,327	$ 42,915
Liabilities:
Other long-term liabilities	21,772	21,969	31,959
Equity:
Accumulated other comprehensive income /(loss)	3,114	(217)	(480)
Accumulated deficit	(594,929)	(333,446)	(330,517)
Noncontrolling interest	$ 13,471	14,797	$ 14,422
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
Assets:
Unbilled receivable		16,307
Equity:
Accumulated deficit		16,307
Adjustment | Accounting Standards Update 2016-16
Assets:
Other non-current assets		(28,588)
Liabilities:
Other long-term liabilities		(9,990)
Equity:
Accumulated other comprehensive income /(loss)		263
Accumulated deficit		(19,236)
Noncontrolling interest		$ 375