Financial Information of Registrant (Parent Company) (Detail 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income (loss)	$ 21,968	$ 2,120	$ 3,469	$ 511	$ 3,158	$ 1,932	$ 2,066	$ 2,024	$ 28,068	$ 9,180	$ (9,040)
Investment income and equity in earnings from other investments									(85)	(399)
Stock-based compensation									185	243	604
Deferred income taxes									(19,223)	(2)	3
Other									224	280	330
Cash flows from investing activities:
Dividends from subsidiary									2,000
Maturities of investments, available-for-sale									19,941	21,769	41,969
Cash flows from financing activities:
Net proceeds from issuance of common stock									74	51	52
Net increase in cash and cash equivalents									30,396	12,929	35,353
Cash and cash equivalents, beginning of year				72,033				59,104	72,033	59,104	23,751
Cash and cash equivalents, end of year	102,429				72,033				102,429	72,033	59,104
Parent Company [Member]
Cash flows from operating activities:
Net income (loss)									28,068	9,180	(9,040)
Investment income and equity in earnings from other investments									(23,804)	(11,657)	6,830
Stock-based compensation									185	243	604
Deferred income taxes									(7,871)	(2)	1
Other									30	(4)	(6)
Change in assets and liabilities									3,197	790	792
Net cash used in operating activities									(195)	(1,450)	(819)
Cash flows from investing activities:
Dividends from subsidiary									7,425	6,635	5,150
Maturities of investments, available-for-sale											3,518
Improvements to foreclosed real estate									(2)	(2)	(2)
Investments in subsidiaries									(44)		(13,000)
Net cash provided by investing activities									7,379	6,633	(4,334)
Cash flows from financing activities:
Net proceeds from issuance of common stock									74	51	52
Net cash provided by (used in) financing activities									74	51	52
Net increase in cash and cash equivalents									7,258	5,234	(5,101)
Cash and cash equivalents, beginning of year				8,578				3,344	8,578	3,344	8,445
Cash and cash equivalents, end of year	$ 15,836				$ 8,578				$ 15,836	$ 8,578	$ 3,344