Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes [Line Items]
Statutory federal corporate tax rate	35.00%
Valuation allowance	$ 1,763,000	$ 24,224,000
Change in the total valuation allowance	22,400,000	4,200,000	1,200,000
Change in the valuation allowance related to unrealized change in investments	1,200,000		500,000
Utilization of valuation allowance associated with net operating loss carry forwards	9,800,000	8,600,000
Changes in calculation allowance of income tax		1,900,000
AMT credit carryforwards	2,004,000	1,784,000
State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Gross Federal NOL carryforwards	7,100,000
NOL carryforwards expire date	2020
Domestic Country [Member]
Income Taxes [Line Items]
Gross Federal NOL carryforwards	$ 17,700,000
NOL carryforwards expire date	2031