Net Income (Loss) Per Common Share (Dilutive Common Share Equivalents) (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Weighted-average common shares outstanding, basic (in shares)	76,137,751	74,385,446	75,840,604	74,182,929
Effect of dilutive securities (in shares)	2,763,850	3,902,821	3,173,153	3,603,819
Weighted-average common shares outstanding, diluted (in shares)	78,901,601	78,288,267	79,013,757	77,786,748
RSUs and PRSUs
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities (in shares)	489,080	1,018,066	755,731	768,172
Stock options
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities (in shares)	2,274,770	2,860,430	2,413,951	2,830,587
Employee stock purchase plan
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Effect of dilutive securities (in shares)	0	24,325	3,471	5,060