Debt - Narrative (Details) - Convertible Senior Notes 0.375 Percent Due 2018 and Convertible Senior Notes 1.25 Percent Due 2020	3 Months Ended
	Mar. 31, 2020 item
Convertible Notes
Number of days within 30 consecutive trading days in which the price of the entity's common stock must exceed the conversion price for the notes to be converted	20 days
Number of consecutive trading days during which the closing price of the entity's common stock must exceed the conversion price for at least 20 days in order for the notes to be convertible	30 days
Percentage of the closing sales price of common stock that the conversion price must exceed in order for the notes to be convertible (as a percent)	130.00%
Number of consecutive business days immediately after any five consecutive trading day period during the note measurement period	5
Number of consecutive trading days before five consecutive business days during the note measurement period	5
Conversion ratio, principal amount of note	1,000
Percentage of the trading price to the product of the last reported sale price of the common stock and the conversion rate, maximum (as a percent)	98.00%
Number of scheduled trading days preceding relevant maturity date at which Notes are convertible regardless of other circumstances	2 days