Restructuring Charges - Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Changes in restructuring accrual
Balance at the beginning of the period	$ 2,841	$ 2,213	$ 1,520
Provision	1,097	6,006	7,395
Payments	(3,659)	(5,378)	(6,702)
Balance at the end of the period	279	2,841	2,213
Non-cash charges related to share based compensation	12,703	15,270	16,074
Personnel severance and related costs
Changes in restructuring accrual
Balance at the beginning of the period	2,841	2,143	1,520
Provision	1,097	5,803	4,681
Payments	(3,659)	(5,105)	(4,058)
Balance at the end of the period	$ 279	2,841	2,143
Facility Related Costs and Other
Changes in restructuring accrual
Balance at the beginning of the period		70
Provision		203	2,714
Payments		(273)	(2,644)
Balance at the end of the period			70
Restructuring
Changes in restructuring accrual
Non-cash charges related to share based compensation		$ 400	$ 1,200