Employee Benefit Plans (Narrative) (Details) $ in Thousands	3 Months Ended		8 Months Ended	12 Months Ended
	Mar. 31, 2017 shares	Mar. 31, 2016 shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2018 USD ($) item shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2016 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) | shares				0	632,000	825,000
Capitalized stock-based compensation				$ 319	$ 459
Options outstanding (in shares) | shares			2,219,000	2,219,000	2,478,000
Award vesting period				4 years
Total unrecognized compensation cost related to unvested stock options			$ 7,700	$ 7,700
Total unrecognized compensation cost, weighted- average period of recognition				1 year
Total intrinsic value of option exercised				$ 1,800	$ 41,600	$ 37,000
Proceeds from exercise of common stock options				1,395	14,267	$ 16,070
Excess tax benefit, share-based compensation				$ 400	$ 15,800
Dividend yield				0.00%	0.00%	0.00%
Stock-based compensation expense				$ 18,088	$ 25,649	$ 27,180
Issuance of common stock under Employee Stock Purchase Plan (in shares) | shares				18,037	48,443
Proceeds from issuance of common stock under Employee Stock Purchase Plan				$ 869	$ 2,681	2,194
Issuance of common stock under Employee Stock Purchase Plan				$ 869	2,681	2,194
Shares available under ESPP | shares				2,234,942
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				$ 2,800	2,500	1,800
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			5,400,000	5,400,000
2000 Stock Option/Issuance Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares) | shares			53,000	53,000
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 200	600	600
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%
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense				$ 12,000	11,800	9,800
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
Stock-based compensation expense				$ 6,200	$ 13,600	$ 16,800
Total unrecognized compensation cost related to unvested stock units			$ 9,500	$ 9,500
Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units granted (in shares) | shares	343,000	263,000		0
Maximum percentage of performance-based restricted stock units				200.00%	200.00%	150.00%
Performance vesting target achieved				72.00%	56.00%	81.00%
Previously Reported | Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance vesting target achieved					130.00%	130.00%
Non-executive employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			100
Executive officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense			$ 1,200