Employee Benefit Plans (Detail) - Assumptions Used to Determine Accumulated Benefit Obligations	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Retirement Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	3.58%	4.11%
Measurement date	December 31, 2014	December 31, 2013
Post Retirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate	2.99%	3.95%
Measurement date	December 31, 2014	December 31, 2013