Equity-Based Compensation - Changes in Restricted Stock (Detail) - Equity Award - $ / shares	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Number of shares, issued and unvested beginning of period	3,508,624	3,755,275	3,738,582	1,185,071	3,755,275	1,185,071	1,185,071
Number of shares, granted	140,416	441,256	135,000	3,095,948
Number of Shares, Vested	(63,017)	(644,247)	(61,647)	(175,771)
Number of Shares, Forfeited		(43,660)		(366,666)
Number of shares, issued and unvested end of period	3,586,023	3,508,624	3,811,935	3,738,582	3,586,023	3,811,935	3,755,275
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted average grant date fair value, issued and unvested beginning balance	$ 15.75	$ 15.94	$ 15.70	$ 9.52	$ 15.94	$ 9.52	$ 9.52
Weighted Average Grant Date Fair Value, Granted	13.17	16.21	17.41	17.21
Weighted Average Grant Date Fair Value, Vested	10.80	19.70	10.52	12.68
Weighted Average Grant Date Fair Value, Forfeited		17.85		9.96
Weighted average grant date fair value, issued and unvested ending balance	$ 15.74	$ 15.75	$ 15.84	$ 15.70	$ 15.74	$ 15.84	$ 15.94