Stockholder's Equity (Details) (USD $)	3 Months Ended			9 Months Ended	1 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2014	Mar. 31, 2015
Stock-Based Compensation
Stock-based compensation expense (in dollars)	$ 1,300,000	$ 1,500,000
Common Class A
Equity Incentive Plans
Shares authorized for issuance	4,000,000				4,000,000
Employee and Directors Stock Options
Stock-Based Compensation
Unrecognized compensation cost related to non-vested stock options (in dollars)	3,300,000				3,300,000
Weighted-average periods over which unrecognized compensation cost recognized	2 years 1 month 6 days
Estimated forfeitures (as a percent)	1.50%				1.50%
Number of shares
Outstanding at the beginning of the period (in shares)		1,870,000		1,870,000
Granted (in shares)				65,000
Outstanding at the end of the period (in shares)			1,870,000	1,935,000
Vested at the end of the period (in shares)				670,000
Exercisable at the end of the period (in shares)				670,000
Weighted-average exercise price
Outstanding at the beginning of the period (in dollars per share)		$ 11.23		$ 11.23
Granted (in dollars per share)				$ 13.49
Outstanding at the end of the period (in dollars per share)			$ 11.23	$ 11.30
Vested at the end of the period (in dollars per share)				$ 11.07
Exercisable at the end of the period (in dollars per share)				$ 11.07
Weighted-average remaining contractual term
Outstanding at the beginning of the period			8 years 4 months 24 days	8 years 2 months 12 days
Granted				6 years 10 months 24 days
Outstanding at the end of the period			8 years 4 months 24 days	8 years 2 months 12 days
Vested at the end of the period				7 years 10 months 24 days
Exercisable at the end of the period				7 years 10 months 24 days
Aggregate intrinsic value
Outstanding at the beginning of the period (in dollars)		4,721,000		4,721,000
Outstanding at the end of the period (in dollars)			4,721,000	3,423,000
Vested at the end of the period (in dollars)				1,315,000
Exercisable at the end of the period (in dollars)				1,315,000
Weighted average grant date fair value of options granted (in dollars per share)	$ 4.48
Valuation assumptions
Dividend yield (as a percent)	0.00%
Restricted Stock
Stock-Based Compensation
Unrecognized compensation cost related to non-vested restricted stock (in dollars)	$ 2,800,000				$ 2,800,000
Weighted-average periods over which unrecognized compensation cost recognized	1 year 1 month 6 days
Number of shares
Outstanding at the beginning of the period (in shares)	719,000
Outstanding at the end of the period (in shares)	719,000				719,000
Weighted-average grant date fair value
Outstanding at the beginning of the period (in dollars per share)	$ 9.82
Outstanding at the end of the period (in dollars per share)	$ 9.82				$ 9.82
Restricted Stock | Common Class A
Equity Incentive Plans
Shares available for issuance	900,000				900,000
Time Based Restricted Stock and Stock Option
Equity Incentive Plans
Number of equal annual installments for vesting of awards	3				3
Time Based Stock Option | Black Scholes Pricing Model
Valuation assumptions
Risk-free interest rate, minimum (as a percent)	1.77%	1.76%		1.77%
Risk-free interest rate, maximum (as a percent)	2.12%	1.92%
Volatility, minimum (as a percent)	27.50%	28.40%
Volatility, maximum (as a percent)	29.50%	30.90%
Weighted-average expected term	6 years 10 months 24 days
Time Based Stock Option | Minimum | Black Scholes Pricing Model
Valuation assumptions
Weighted-average expected term		6 years		0 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)					$ 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	10				10
Event Based Stock Option
Aggregate intrinsic value
Unvested options	300,000				300,000
Event Based Restricted Stock
Number of shares
Outstanding at the end of the period (in shares)	200,000				200,000