Commitments and Contingencies - Commitments under Operating Lease Agreements (Details) - USD ($) $ in Millions		Jun. 30, 2019	Mar. 31, 2019
Amounts due on operating lease liabilities as of June 30, 2019
2020	[1]	$ 16
2021		19
2022		20
2023		12
2024		10
Thereafter		61
Total		138
Present value discount		(20)
Total operating lease liability		$ 118
Future minimum lease payments as of March 31, 2019
2020			$ 22
2021			19
2022			20
2023			12
2024			10
Thereafter			61
Total			$ 144

[1] Amounts due on operating lease liabilities as of June 30, 2019 excludes the three months ended June 30, 2019.