Net Income (Loss) Per Common Share (Dilutive Common Share Equivalents) (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted-average common shares outstanding, basic (in shares)	75,433,008	74,715,592	75,722,117	74,362,211
Effect of dilutive securities (in shares)	2,325,273	4,656,899	2,854,782	3,952,508
Weighted-average common shares outstanding, diluted (in shares)	77,758,281	79,372,491	78,576,899	78,314,719
RSUs and PRSUs
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities (in shares)	254,262	1,616,072	562,381	1,083,237
Stock options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities (in shares)	2,071,011	3,040,827	2,286,727	2,869,271
Employee stock purchase plan
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities (in shares)	0	0	5,674	0