Commitments and Contingencies - Additional Information (Details) £ in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($) $ / £	Sep. 30, 2020 GBP (£) $ / £	Mar. 31, 2019 USD ($) $ / £	Mar. 31, 2019 GBP (£) $ / £
Commitments And Contingencies Disclosure [Abstract]
Purchase Commitments	$ 19.8
Long-term purchase commitment, Amount	$ 20.3
Defined benefit plan, estimated future employer contributions in current fiscal year, description	We have a contributory defined benefit plan that covers certain employees in the United Kingdom.  As of September 30, 2020, the unfunded liability for this defined benefit plan was approximately $30.7 million.  An actuarial valuation was performed as of March 31, 2019, resulting in a deficit of approximately GBP 26.7 million (approximately $34.7 million based on a GBP: USD exchange rate of 1.3:1). As a result of this valuation we have agreed to a revised schedule of contributions of GBP 2.0 million (approximately $2.6 million based on a GBP: USD exchange rate of 1.3:1) to be paid in annual installments with effect from April 1, 2020 to address the deficit revealed by the valuation (with the first payment made by March 31, 2021, and payments to be made by December 31 each year thereafter). These contributions, together with the assumed asset outperformance, are expected to eliminate the deficit by December 31, 2028. Further, we will pay GBP 0.2 million in annual installments effective April 1, 2020 to cover expenses.
Defined benefit plan, annual future benefit payments	$ 2.6	£ 2.0
Unfunded liability of defined benefit plan, deficit			$ 34.7	£ 26.7
Defined benefit plan, additional annual future benefit payments | £		£ 0.2
GBP:USD exchange rate | $ / £	1.3	1.3	1.3	1.3
Unfunded liability of defined benefit plan	$ 30.7