Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Deferred tax asset, net	42,100,000	$ 41,700,000
Alternative minimum tax credit carryforward	11,000,000
Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax years open for examination	2011
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax years open for examination	2014
Le Mars [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance related to the portion of operating loss carryforwards	440,778
Operating loss carryforwards	3,900,000
Operating loss carryforwards expiration period	2020
Operating loss carryforwards annual limitations in amount on use	376,000