Leases - Additional Information (Details) $ in Thousands		1 Months Ended	3 Months Ended
	Jan. 01, 2019 USD ($) ft² Option	Mar. 31, 2018 ft²	Mar. 31, 2019 USD ($) lease	Dec. 31, 2018 USD ($)
Lessee Lease Description [Line Items]
Area of real estate property		220,000
Lessee operating lease term of option to extend		10 years
Number of additional operating leases | lease			2
Weighted average incremental borrowing rate			4.46%
Weighted average remaining lease term			4 years 1 month 6 days
Right-of-use assets | $	$ 20,100		$ 18,010
Operating lease liability | $	$ 22,100		19,815	$ 53,601
Payments for operating leases | $			2,300
Operating lease expense | $			$ 2,100
MASSACHUSETTS | Corporate office and administrative space expire in 2021
Lessee Lease Description [Line Items]
Area of real estate property	175,000
Maximum number of option to extend lease term | Option	2
Lessee operating lease term of option to extend	5 years
Operating lease, existence of option to extend	true
MASSACHUSETTS | Corporate office and administrative space expire in 2020
Lessee Lease Description [Line Items]
Area of real estate property	67,000
Maximum number of option to extend lease term | Option	2
Lessee operating lease term of option to extend	1 year
Operating lease, existence of option to extend	true
Ireland | Corporate office and administrative space expire in 2022
Lessee Lease Description [Line Items]
Area of real estate property	14,600
Lessee operating lease term of option to extend	5 years
Operating lease, existence of option to extend	true
Washington | Corporate office and administrative space expire In 2029
Lessee Lease Description [Line Items]
Area of real estate property	7,000
Lessee operating lease term of option to extend	5 years
Operating lease, existence of option to extend	true