Income Taxes - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Other deferred tax assets	$ 43,400,000	$ 42,700,000
Alternative minimum tax credit carryforward	$ 7,600,000
Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax years open for examination	2013
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Tax years open for examination	2016
Le Mars [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance related to the portion of operating loss carryforwards	$ 440,778
Operating loss carryforwards	$ 3,600,000
Operating loss carryforwards expiration period	2020
Operating loss carryforwards annual limitations in amount on use	$ 376,000