Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Statutory federal corporate tax rate	35.00%
Valuation allowance	$ 1,746	$ 1,763
Change in the total valuation allowance		22,400	$ 4,300
Change in the valuation allowance related to unrealized change in investments		1,200
Utilization of valuation allowance associated with net operating loss carry forwards		9,800	8,600
Change in valuation allowance of income tax			$ 1,900
AMT credit carryforwards	2,015	$ 2,004
Domestic Country
Income Taxes [Line Items]
Gross Federal NOL carryforwards	$ 19,600
NOL carryforwards expire date	2031
State And Local Jurisdiction
Income Taxes [Line Items]
Gross Federal NOL carryforwards	$ 8,500
NOL carryforwards expire date	2020