Commitments and Contingencies - Leases (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 03, 2017	Dec. 30, 2016
Operating Leased Assets [Line Items]
Facility Purchase Price							$ 720,000
Payment towards purchase price of Tarrytown facility				$ 57,000
Aggregate funding advanced by the participants						$ 720,000
Reimbursement received by the Company						57,000
Initial term of lease		5 years
Potential extended term of lease		5 years
Tarrytown facility capital and facility lease obligations						$ 720,000
Interest expense in connection with capital and facility leases			$ 19,500	5,400	$ 9,700
Commitments under operating leases [Abstract]
2018			8,963
2019			3,912
2020			3,139
2021			2,431
2022			1,927
Thereafter			1,506
Total			21,878
Rent expense under operating leases [Abstract]
Rent expense under operating leases			4,289	16,713	15,202
Facilities
Commitments under operating leases [Abstract]
2018			2,866
2019			3,095
2020			2,713
2021			2,386
2022			1,901
Thereafter			1,498
Total			14,459
Rent expense under operating leases [Abstract]
Rent expense under operating leases			3,138	15,861	14,659
Equipment
Commitments under operating leases [Abstract]
2018			6,097
2019			817
2020			426
2021			45
2022			26
Thereafter			8
Total			7,419
Rent expense under operating leases [Abstract]
Rent expense under operating leases			$ 1,151	$ 852	$ 543
Tarrytown lease transaction [Member]
Operating Leased Assets [Line Items]
Out of period adjustment	$ 30,100