Stockholders' Equity (Details 2) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) item $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares
Equity incentive plans
Shares available for issuance	800
Stock-based compensation
Stock-based compensation expense (in dollars) | $	$ 5,600	$ 5,900	$ 7,200
Common Class A
Equity incentive plans
Shares authorized for issuance	4,000
Employee and Directors Stock Options
Equity incentive plans
Granted (in shares)	215	140	1,730
Vested at the end of the period (in shares)	1,065
Stock-based compensation
Unrecognized compensation cost related to non-vested stock options (in dollars) | $	$ 2,300
Weighted-average periods over which unrecognized compensation cost recognized	2 years 1 month 6 days
Estimated forfeitures (as a percent)	1.50%
Valuation assumptions
Dividend yield (as a percent)	0.00%
Number of shares
Outstanding at the beginning of the period (in shares)	1,870	1,730
Granted (in shares)	215	140	1,730
Exercised (in shares)	(15)
Forfeited or expired (in shares)	(27)
Outstanding at the end of the period (in shares)	2,043	1,870	1,730
Vested at the end of the period (in shares)	1,065
Exercisable at the end of the period (in shares)	1,065
Weighted-average exercise price
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 11.23
Granted (in dollars per share) | $ / shares	13.61	$ 11.56	$ 11.20
Exercised (in dollars per share) | $ / shares	10.60
Forfeited or expired (in dollars per share) | $ / shares	10.60		$ 11.20
Outstanding at the end of the period (in dollars per share) | $ / shares	11.49	$ 11.23
Vested at the end of the period (in dollars per share) | $ / shares	11.33
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 11.33
Weighted-average remaining contractual term
Granted	6 years 2 months 12 days	9 years 8 months 12 days	9 years 3 months 18 days
Outstanding	7 years 7 months 6 days	8 years 4 months 24 days	9 years 3 months 18 days
Vested at the end of the period	7 years 3 months 18 days
Exercisable at the end of the period	7 years 3 months 18 days
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars) | $	$ 4,721	$ 2,208
Granted (in dollars) | $			$ 1,157
Outstanding at the end of the period (in dollars) | $	6,740	$ 4,721	$ 2,208
Vested at the end of the period (in dollars) | $	3,696
Exercisable at the end of the period (in dollars) | $	$ 3,696
Weighted average grant date fair value of options granted (in dollars per share) | $ / shares	$ 4.13	$ 3.75	$ 4.21
Restricted Stock
Equity incentive plans
Granted (in shares)	99	79	1,195
Stock-based compensation
Unrecognized compensation cost related to non-vested restricted stock (in dollars) | $	$ 3,700
Weighted-average periods over which unrecognized compensation cost recognized	10 months 24 days
Number of shares
Outstanding at the beginning of the period (in shares)	719	945
Granted (in shares)	99	79	1,195
Vested (in shares)	(324)	(305)	(250)
Outstanding at the end of the period (in shares)	494	719	945
Weighted-average grant date fair value
Outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 9.82	$ 10.18
Granted (in dollars per share) | $ / shares	12.42	11.34	$ 9.81
Vested (in dollars per share) | $ / shares	10.65	11.33	8.41
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 9.79	$ 9.82	$ 10.18
Time Based Restricted Stock and Stock Option
Equity incentive plans
Number of equal annual installments for vesting of awards | item	3
Time Based Stock Option | Black Scholes Pricing Model
Valuation assumptions
Risk-free interest rate, minimum (as a percent)	1.76%	1.76%	0.93%
Risk-free interest rate, maximum (as a percent)	2.12%	1.92%	2.03%
Volatility, minimum (as a percent)	25.80%	28.40%	34.40%
Volatility, maximum (as a percent)	29.50%	30.90%	36.70%
Weighted-average expected term	6 years 3 months 18 days		6 years
Time Based Stock Option | Black Scholes Pricing Model | Maximum
Valuation assumptions
Weighted-average expected term		6 years 3 months 18 days
Time Based Stock Option | Black Scholes Pricing Model | Minimum
Valuation assumptions
Weighted-average expected term		6 years
Time Based Restricted Stock
Weighted-average grant date fair value
Vesting period	3 years
Event Based Restricted Stock and Stock Option | Common Class A
Equity incentive plans
Closing price per share to be attained for vesting of awards to begin (in dollars per share) | $ / shares	$ 15.00
Event Based Restricted Stock and Stock Option | Common Class A | Minimum
Equity incentive plans
Number of trading days on which the closing price per share should attain the specified price per share for vesting of awards to begin | item	10
Event Based Stock Option
Aggregate intrinsic value
Unvested options	300
Event Based Restricted Stock
Aggregate intrinsic value
Unvested options	200