Stockholders' Equity - Common and Convertible Preferred Stock (Details)		12 Months Ended
	Apr. 21, 2015 shares	Dec. 31, 2019 USD ($) vote $ / shares shares	Dec. 31, 2018 $ / shares shares	Dec. 31, 2017 shares	Dec. 31, 2016 shares
Class of Stock [Line Items]
Common stock, shares authorized (in shares)		1,400,000,000	1,400,000,000
Preferred stock, shares authorized (in shares)		25,000,000	25,000,000
Common stock, shares outstanding (in shares)		118,342,772	119,771,702
Common stock, shares issued (in shares)		118,342,772	119,771,702
Common stock, votes per share of stock held | vote		1
Dividends declared for common stock | $		$ 0
Common stock, par value (in dollars per share) | $ / shares		$ 0.001	$ 0.001
Common Stock
Class of Stock [Line Items]
Common stock, shares outstanding (in shares)		118,342,772	119,771,702	121,769,238	115,973,039
Conversion of preferred stock upon public offering (in shares)	53,448,243
Convertible senior notes
Class of Stock [Line Items]
Convertible preferred stock outstanding (in shares)		0	0	0