Earnings Per Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Weighted average shares outstanding:
Basic (in shares)	34,913,000	34,581,000	34,849,000	34,589,000
Stock options and ESPP shares (in shares)	0	473,000	113,000	484,000
Unvested RSUs (in shares)	0	196,000	381,000	348,000
Diluted (in shares)	34,913,000	35,250,000	35,343,000	35,421,000
Dilutive securities included in the calculation (in shares)	0	1,646,000	1,366,000	1,786,000
Anti-dilutive securities excluded from the calculation (in shares)	2,370,000	1,091,000	1,000,000	1,086,000
RSUs
Weighted average shares outstanding:
Anti-dilutive securities excluded from the calculation (in shares)	345,000
Stock options
Weighted average shares outstanding:
Anti-dilutive securities excluded from the calculation (in shares)	110,000