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Restructuring Expenses - Changes to Restructuring Charges (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Restructuring Reserve [Roll Forward]
Balance accrued at December 31, 2019					$ 797
Restructuring charges	$ 0	$ 8,200	$ 0	$ 7,400	8,197	$ 7,420
Balance accrued at September 30, 2020	1,596				1,596
2019 Restructuring
Restructuring Reserve [Roll Forward]
Balance accrued at December 31, 2019					797
Restructuring charges					0
Balance accrued at September 30, 2020	171				171
2020 Restructuring
Restructuring Reserve [Roll Forward]
Balance accrued at December 31, 2019					0
Restructuring charges					8,197
Balance accrued at September 30, 2020	$ 1,425				1,425
Workforce Reduction Payments
Restructuring Reserve [Roll Forward]
Payments for restructuring					(7,291)
Workforce Reduction Payments \| 2019 Restructuring
Restructuring Reserve [Roll Forward]
Payments for restructuring					(626)
Workforce Reduction Payments \| 2020 Restructuring
Restructuring Reserve [Roll Forward]
Payments for restructuring					(6,665)
Other Payments
Restructuring Reserve [Roll Forward]
Payments for restructuring					(107)
Other Payments \| 2019 Restructuring
Restructuring Reserve [Roll Forward]
Payments for restructuring					0
Other Payments \| 2020 Restructuring
Restructuring Reserve [Roll Forward]
Payments for restructuring					$ (107)