Commitment and Contingencies - Lease Narrative (Details) $ in Thousands, € in Millions	1 Months Ended		3 Months Ended		6 Months Ended
	Mar. 31, 2016	Aug. 31, 2015 EUR (€) ft²	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Aug. 31, 2015 USD ($)
Loss Contingencies [Line Items]
Operating Leases, Rent Expense, Net			$ 200	$ 600	$ 500	$ 1,000
Future minimum payments due			1,931		1,931
Dublin, Ireland [Member]
Loss Contingencies [Line Items]
Operating Leases, Area of office space (in sq ft) | ft²		6,258
Operating leases, term of contract (in years)		10 years
Operating Leases, Rent review term (in years)		5 years
Operating leases, Option to terminate, date		Aug. 31, 2020
Future minimum payments due		€ 2.0	$ 1,900		$ 1,900		$ 2,300
Built-to-Suit Lease [Member]
Loss Contingencies [Line Items]
Build-to-suit lease expiration date	Dec. 31, 2023