Insurance Activity - Components of Liability for Losses and Loss Adjustment Reserves (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Effects of Reinsurance [Line Items]
Total losses and loss adjustment reserves	$ 6,582	$ 18,947	$ 44,314
Case-basis reserves [Member]
Effects of Reinsurance [Line Items]
Total losses and loss adjustment reserves	4,428	16,538
IBNR reserves [Member]
Effects of Reinsurance [Line Items]
Total losses and loss adjustment reserves	78	110
Premium deficiency reserves [Member]
Effects of Reinsurance [Line Items]
Total losses and loss adjustment reserves	$ 2,076	$ 2,299