Financial Information of Registrant (Parent Company) (Detail 1) - USD ($) $ 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
Statement of Operations
Interest income									$ 4,719	$ 4,649	$ 5,024
Equity in income (loss) of subsidiaries, net of tax									440	427	396
Income (loss) before income taxes	$ 3,139	$ 3,351	$ (1,480)	$ 1,576	$ (5,822)	$ (327)	$ (30,607)	$ (8,374)	6,586	(45,130)	(2,572)
Provision (benefit) for income taxes									15,190	(15,848)	(642)
Net loss	$ (10,429)	$ 1,998	$ (903)	$ 730	$ (3,545)	$ (333)	$ (19,899)	$ (5,505)	(8,604)	(29,282)	(1,930)
Parent Company
Statement of Operations
Interest income									2,944	2,283	1,328
Equity in income (loss) of subsidiaries, net of tax									3,390	(27,428)	(441)
Expenses									(7,180)	(4,508)	(4,238)
Income (loss) before income taxes									(846)	(29,653)	(3,351)
Provision (benefit) for income taxes									7,758	(371)	(1,421)
Net loss									$ (8,604)	$ (29,282)	$ (1,930)