Insurance Activity - Components of Liability for Losses and Loss Adjustment Reserves (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Effects of Reinsurance [Line Items]
Total losses and loss adjustment reserves	$ 811	$ 5,063	$ 18,947
Case-basis reserves [Member]
Effects of Reinsurance [Line Items]
Total losses and loss adjustment reserves	553	4,193
IBNR reserves [Member]
Effects of Reinsurance [Line Items]
Total losses and loss adjustment reserves		75
Premium deficiency reserves [Member]
Effects of Reinsurance [Line Items]
Total losses and loss adjustment reserves	$ 258	$ 795