Financial Information of Registrant (Parent Company) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Cash and cash equivalents	$ 115,587	$ 102,429	$ 72,033	$ 59,104
Deferred tax asset	18,301	16,521
Other assets	6,950	5,962
TOTAL ASSETS	402,127	328,445
Liabilities:
Debentures payable	40,256	40,211
Term loan from principal stockholder	29,753
Other liabilities	15,606	13,453
Stockholders' equity	103,670	106,964	76,932	72,793
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	402,127	328,445
Parent Company
ASSETS
Investment in subsidiaries, at equity in net assets	132,430	126,494
Cash and cash equivalents	8,095	15,836	$ 8,578	$ 3,344
Loan to wholly-owned subsidiary	30,010
Deferred tax asset	8,649	7,965
Other assets	2,142	2,144
TOTAL ASSETS	181,326	152,439
Liabilities:
Debentures payable	40,256	40,211
Term loan from principal stockholder	29,753
Other liabilities	7,647	5,264
Stockholders' equity	103,670	106,964
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 181,326	$ 152,439