Quarterly Results of Operations - Summary of Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net revenue	$ 73,460	$ 334,555	$ 70,509	$ 57,510	$ 70,291	$ 65,281	$ 64,829	$ 58,113	$ 536,034	$ 258,514	$ 254,134
Net income applicable to common stockholders	$ 12,972	$ 157,208	$ 3,495	$ 2,618	$ 7,003	$ 5,415	$ 5,717	$ 2,270	$ 176,293	$ 20,405	$ 25,625
Net income per share, basic	$ 0.14	$ 1.74	$ 0.04	$ 0.03	$ 0.08	$ 0.06	$ 0.06	$ 0.03	$ 1.95	$ 0.23	$ 0.29
Net income per share, diluted	$ 0.14	$ 1.71	$ 0.04	$ 0.03	$ 0.08	$ 0.06	$ 0.06	$ 0.02	$ 1.92	$ 0.22	$ 0.28