Stockholders' Equity and Equity Compensation Plans (Tables)

6 Months Ended

Jun. 30, 2019

Stockholders Equity Note [Abstract]

Summary of Unvested Restricted Common Stock Activity

Stock-Based Awards. A summary of our unvested restricted common stock activity during the quarter and six months ended June 30, 2019 is as follows (shares in thousands):

	Quarter Ended					Six Months Ended
	June 30, 2019					June 30, 2019
	Shares			Weighted- Average Grant Date Fair Value		Shares			Weighted- Average Grant Date Fair Value
Unvested awards, beginning		1,299		$	42.04		1,145		$	41.64
Awards granted		7			46.12		483			40.85
Awards forfeited/cancelled		(110	)		42.70		(114	)		42.68
Awards vested		(16	)		42.05		(334	)		38.87
Unvested awards, ending		1,180		$	42.00		1,180		$	42.00