Employee Benefit Plans (Narrative) (Details) $ in Thousands	3 Months Ended					12 Months Ended
	Mar. 31, 2016 shares	Mar. 31, 2015 shares	Sep. 30, 2014 shares	Jun. 30, 2014 shares	Mar. 31, 2014 shares	Dec. 31, 2016 USD ($) item shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						4 years
Total unrecognized compensation cost related to unvested stock options						$ 21,000
Total unrecognized compensation cost, weighted- average period of recognition						2 years 7 months 28 days
Total intrinsic value of option exercised						$ 37,000	$ 17,100	$ 28,400
Cash received from option exercise under all share-based payment arrangements						16,100	6,600	6,700
Excess tax benefits related to stock-based compensation						$ 17,900	$ 11,200	$ 10,400
Dividend yield						0.00%	0.00%	0.00%
Stock-based compensation expense						$ 30,268	$ 20,606	$ 14,558
Issuance of common stock under Employee Stock Purchase Plan, Shares | shares						52,727
Issuance of common stock under Employee Stock Purchase Plan						$ 2,194	2,145	2,100
Shares available under ESPP | shares						1,534,692
Annual increase in shares available under ESPP as percentage of shares outstanding						1.00%
Allowable payroll deduction, percent						25.00%
Number of offering periods during the year | item						4
Duration of offering period						3 months
Purchase price as fair value of common stock, percent						85.00%
Employee eligibility requirement						1000 hours
Employee contribution 401(k)						85.00%
Employer discretionary 401 (k) contribution, percent of match						40.00%
Employer discretionary 401 (k) contribution, percent of gross pay matched						6.00%
Contribution to 401(k) Plan						$ 1,800	1,300	1,000
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option, expiration period						10 years
Annual increase in shares available under ESPP | shares						500,000
2010 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for issuance | shares						6,200,000
2000 Stock Option/Issuance Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock reserved for issuance | shares						300,000
Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						1 year
Stock vesting percentage						25.00%
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						4 years
Total unrecognized compensation cost, weighted- average period of recognition						1 year 6 months 15 days
Stock-based compensation expense						$ 19,900	$ 13,000	$ 6,000
Total unrecognized compensation cost related to unvested stock units						$ 29,300
Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in shares) | shares	263,000	140,000		199,000	106,500	351,000
Maximum percentage of performance-based restricted stock units						200.00%	150.00%	150.00%
Units forfeited (in shares) | shares			33,000			0