Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			12 Months Ended	3 Months Ended						0 Months Ended		3 Months Ended								3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Jan. 31, 2014	Jul. 31, 2013	Jan. 31, 2013	Jul. 31, 2013	Mar. 31, 2014 $4.00	Mar. 31, 2014 $12.97	Mar. 31, 2014 Stock Options	Mar. 31, 2013 Stock Options	Mar. 31, 2014 Restricted Stock	Mar. 31, 2013 Restricted Stock	Mar. 07, 2014 Performance-based Restricted Stock President	Feb. 04, 2014 Performance-based Restricted Stock President	Mar. 31, 2014 Performance-based Restricted Stock President	Mar. 31, 2014 Options and ESPP	Mar. 31, 2013 Options and ESPP	Mar. 31, 2014 ESPP	Mar. 31, 2013 ESPP	Jan. 31, 2014 ESPP	Jul. 31, 2013 ESPP	Jan. 31, 2013 ESPP	Mar. 31, 2014 ESPP Employee Stock Purchase Plan 2009
Shares
Options outstanding at December 31, 2013 (in shares)	281,000
Options granted (in shares)	0
Options exercised (in shares)	(2,000)
Options forfeited (in shares)	0
Options outstanding at March 31, 2014 (in shares)	279,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares	0
Weighted Average Exercise Price
Options outstanding at December 31, 2013 (usd per share)	$ 8.79
Options granted (usd per share)	$ 0.00
Options exercised (usd per share)	$ 4.00
Options forfeited (usd per share)	$ 0.00
Options outstanding at March 31, 2014 (usd per share)	$ 8.83
Intrinsic value of options exercised	$ 12,800	$ 87,000
Lower Range of Exercise Price							$ 4.00	$ 12.97
Upper Range of Exercise Price							$ 4.00	$ 12.97
Number Outstanding as of March 31, 2014
Options Outstanding, Number of Outstanding as of March 31, 2014 (shares)	279,000						129,000	150,000
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	2 years 6 months 10 days						0 years 2 months 26 days	4 years 5 months 23 days
Options Outstanding, Weighted Average Exercise Price (in dollars per share)	$ 8.83						$ 4.00	$ 12.97
Options Exercisable, Number of Outstanding as of March 31, 2014 (shares)	129,000						129,000
Options Exercisable, Weighted Average Remaining Contractual Life (in years)	0 years 2 months 26 days						0 years 2 months 26 days
Options Exercisable, Weighted Average Exercise Price (in dollars per share)	$ 4.00						$ 4.00
Intrinsic value of stock options outstanding	800,000
Restricted Stock
Unvested as of December 31, 2013 (in shares)											2,310,000
Granted (shares)											192,000		31,250	31,250	0
Vested (shares)											(773,000)
Forfeited (shares)											(95,000)
Unvested as of March 31, 2014 (in shares)											1,634,000
Weighted Average Grant Date Fair Value
Unvested, Beginning Balance (usd per share)											$ 10.01
Granted (usd per share)											$ 11.95	$ 9.25				$ 2.62	$ 1.98
Vested (usd per share)											$ 9.45
Forfeited (usd per share)											$ 9.91
Unvested, Ending Balance (usd per share)											$ 10.52		$ 12.03
Fair value of equity instrument other than options											7,300,000	3,800,000			400,000	44,000	29,000
Shares of restricted stock repurchased to satisfy tax withholding obligations											327,213	174,338
Aggregate intrinsic value of restricted shares											16,600,000
Total unrecognized compensation cost related to non-vested restricted shares											13,700,000				300,000
Total unrecognized compensation cost, weighted-average recognition period											2 years 7 months 6 days												4 months
Stock-based compensation expense	1,188,000	1,304,000							47,000	0	1,200,000	1,300,000			30,000	21,000	18,000
Shares issued under the ESPP			17,640	19,048	20,170	39,218
ESPP, purchase price (usd per share)																				$ 10.26	$ 8.15	$ 7.11
Employee Stock Purchase Program Valuation Assumptions
Expected term																		6 months	6 months
Risk-free rate																		0.06%	0.11%
Expected volatility																		29.30%	19.90%
Dividend yield																		0.00%	0.00%
Intrinsic value of rights outstanding ESPP																							30,000
Compensation costs not yet recognized																							36,000
Cash received from exercise of options and ESPP																$ 200,000	$ 200,000