Stock Options, Employee Stock Purchase Plan and Restricted Stock (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2011	May 02, 2014	Aug. 07, 2009	May 27, 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 15,400,000	$ 13,100,000	$ 7,800,000
Total intrinsic value of stock options exercised	40,300,000	97,400,000	141,700,000
Additional paid-in-capital recorded	14,000,000	10,200,000	8,100,000
Total unrecognized compensation cost	$ 28,100,000
Recognition period for unrecognized compensation cost	2 years 9 months 18 days
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 10,200,000
Recognition period for unrecognized compensation cost	2 years 9 months 18 days
2003 Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)						11,000,000
Vesting period	3 years
Amended 2003 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)				19,000,000			5,000,000.0
Number of shares granted (in shares)	15,800,000
Number of shares exercised (in shares)	10,800,000
Number of shares canceled (in shares)	4,400,000
Number of remaining shares outstanding (in shares)	700,000
Number of additional shares authorized (in shares)				8,000,000.0
Expiration period	5 years
Vesting period	4 years
2014 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)					7,500,000
Number of shares granted (in shares)	4,600,000
Number of shares exercised (in shares)	74,399
Number of shares canceled (in shares)	400,000
Number of remaining shares outstanding (in shares)	4,100,000
2014 Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	5 years
2014 Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)	2,000,000
Share-based compensation expense	$ (300,000)	$ 600,000	$ 400,000
Discount from market price at the beginning or end of the offering period	15.00%
Maximum annual purchases per employee under ESPP	$ 25,000
Maximum annual withholdings per employee for purchases under ESPP	$ 21,250
Maximum number of shares available for purchase per employee (in shares)	15,000
Shares issued under plan (in shares)	1,400,000
Shares issued during period (in shares)	0	0	67,000
ESPP [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of base wages withheld for purchase of stock	1.00%
ESPP [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of base wages withheld for purchase of stock	15.00%