Stockholders' Equity - Schedule of common stock (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued beginning balance (In shares)	70,079,747	70,363,251	70,596,559	69,818,392
Repurchase of common stock (in shares)	(392,700)	(434,766)	(1,175,609)	(594,799)
Awards effectively repurchased for required employee withholding taxes (in shares)	(81,007)	(92,462)	(182,911)	(204,266)
Shares issued ending balance (In shares)	69,991,145	70,573,887	69,991,145	70,573,887
Issuance of common stock from vested restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock from vested restricted stock units (in shares)	213,991	389,875	500,710	1,000,141
Issuance of common stock from exercise of stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock from exercise of stock options (in shares)	58,491	263,464	139,773	469,894
Issuance of common stock for employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock for employee stock purchase plan (in shares)	112,623	84,525	112,623	84,525