Stockholder's Equity (Details 2) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015 USD ($) item $ / shares shares	Jun. 30, 2015 USD ($) item $ / shares shares	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) item $ / shares shares	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) $ / shares shares
Stock-Based Compensation
Stock-based compensation expense (in dollars) | $		$ 1,400	$ 1,700	$ 2,700	$ 3,200
Common Class A
Equity Incentive Plans
Shares authorized for issuance	4,000	4,000		4,000
Employee and Directors Stock Options
Stock-Based Compensation
Unrecognized compensation cost related to non-vested stock options (in dollars) | $	$ 2,800	$ 2,800		$ 2,800
Weighted-average periods over which unrecognized compensation cost recognized				2 years
Estimated forfeitures (as a percent)	1.50%	1.50%		1.50%
Number of shares
Outstanding at the beginning of the period (in shares)				1,870
Granted (in shares)				75
Outstanding at the end of the period (in shares)	1,945	1,945		1,945		1,870
Vested at the end of the period (in shares)	1,027	1,027		1,027
Exercisable at the end of the period (in shares)	1,027	1,027		1,027
Weighted-average exercise price
Outstanding at the beginning of the period (in dollars per share) | $ / shares				$ 11.23
Granted (in dollars per share) | $ / shares				13.30
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 11.31	$ 11.31		11.31		$ 11.23
Vested at the end of the period (in dollars per share) | $ / shares	11.30	11.30		11.30
Exercisable at the end of the period (in dollars per share) | $ / shares	$ 11.30	$ 11.30		$ 11.30
Weighted-average remaining contractual term
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2				7 years 10 months 24 days		8 years 4 months 24 days
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2				7 years 10 months 24 days		8 years 4 months 24 days
Vested at the end of the period				7 years 8 months 12 days
Exercisable at the end of the period				7 years 8 months 12 days
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars) | $				$ 4,721
Outstanding at the end of the period (in dollars) | $	$ 2,296	$ 2,296		2,296		$ 4,721
Vested at the end of the period (in dollars) | $	1,296	1,296		1,296
Exercisable at the end of the period (in dollars) | $	1,296	1,296		$ 1,296
Weighted average grant date fair value of options granted (in dollars per share) | $ / shares				$ 4.36
Valuation assumptions
Dividend yield (as a percent)				0.00%
Restricted Stock
Equity Incentive Plans
Granted (in shares)				74
Stock-Based Compensation
Unrecognized compensation cost related to non-vested restricted stock (in dollars) | $	$ 2,900	$ 2,900		$ 2,900
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
Granted (in shares)				74
Vested (in shares)				(304)
Outstanding at the end of the period (in shares)	489	489		489		719
Weighted-average grant date fair value
Outstanding at the beginning of the period (in dollars per share) | $ / shares				$ 9.82
Granted (in dollars per share) | $ / shares				12.10
Vested (in dollars per share) | $ / shares				10.53
Outstanding at the end of the period (in dollars per share) | $ / shares	$ 9.72	$ 9.72		$ 9.72		$ 9.82
Restricted Stock | Common Class A
Equity Incentive Plans
Shares available for issuance	900	900		900
Time Based Restricted Stock and Stock Option
Equity Incentive Plans
Number of equal annual installments for vesting of awards | item	3	3		3
Time Based Stock Option | Black Scholes Pricing Model
Valuation assumptions
Risk-free interest rate, minimum (as a percent)				1.77%	1.76%
Risk-free interest rate, maximum (as a percent)				2.12%	1.92%
Volatility, minimum (as a percent)				26.20%	28.40%
Volatility, maximum (as a percent)				29.50%	30.90%
Weighted-average expected term				6 years 8 months 12 days
Time Based Stock Option | Minimum | Black Scholes Pricing Model
Valuation assumptions
Weighted-average expected term					6 years
Time Based Stock Option | Maximum | Black Scholes Pricing Model
Valuation assumptions
Weighted-average expected term					6 years 3 months 18 days
Time Based Restricted Stock
Valuation assumptions
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	10		10
Event Based Stock Option
Aggregate intrinsic value
Unvested options	300	300		300
Event Based Restricted Stock
Number of shares
Outstanding at the end of the period (in shares)	200	200		200