Contingency - Additional Information (Detail) - USD ($)				3 Months Ended
	Mar. 31, 2015	Mar. 30, 2015	Mar. 06, 2015	May. 29, 2015
Loss Contingencies [Line Items]
Contingencies description				In accordance with ASC Topic 450, "Contingencies," the Corporation accrues for these contingencies by a charge to income when it is both probable that one or more future events will occur confirming the fact of a loss and the amount of the loss can be reasonably estimated.
Settlement fund to pay claims		$ 4,000,000
Violation Of Telephone Consumer Protection Act [Member]
Loss Contingencies [Line Items]
Damage amount for each violation			$ 500
Willful Violation Of Telephone Consumer Protection Act [Member]
Loss Contingencies [Line Items]
Damage amount for each violation			$ 1,500
Maximum [Member]
Loss Contingencies [Line Items]
Period of funding settlement	20 days