Indebtedness - Carrying Value of Senior Convertible Notes (Parenthetical) (Details)	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2016
2.25% Senior Convertible Notes [Member] | Convertible Notes due 2021 [Member]
Debt Instrument [Line Items]
Interest rate on convertible notes	2.25%		2.25%	2.25%
1.00% Senior Convertible Notes [Member] | Convertible Notes due 2023 [Member]
Debt Instrument [Line Items]
Interest rate on convertible notes	1.00%
0.375% Senior Convertible Notes [Member] | Convertible Notes due 2025 [Member]
Debt Instrument [Line Items]
Interest rate on convertible notes	0.375%	0.375%	0.375%