Convertible Notes - Narrative (Details) - Convertible Senior Notes 1.25 Percent Due 2020	12 Months Ended
	Dec. 31, 2020 item $ / shares	Dec. 31, 2019
Convertible Notes
Interest rate of debt (as a percent)	1.25%	1.25%
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	0.193207
Conversion ratio, principal amount, denominator	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%
Conversion price per share (in dollars per share) | $ / shares	$ 51.76