Stockholders' Equity and Equity Compensation Plans (Tables)

3 Months Ended

Mar. 31, 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 first quarter of 2019 is as follows (shares in thousands):

	Quarter Ended
	March 31, 2019
	Shares			Weighted- Average Grant Date Fair Value
Unvested awards, beginning		1,145		$	41.64
Awards granted		476			40.78
Awards forfeited/cancelled		(4	)		43.43
Awards vested		(318	)		38.71
Unvested awards, ending		1,299		$	42.04