Derivative Instruments and Hedging Activities - Schedule of Gross Amounts of Derivative Assets and Derivative Liabilities (Detail) (Not Designated as Hedging Instruments [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Not Designated as Hedging Instruments [Member]
Derivatives not Designated as Hedging Instruments
Gross amounts recognized	$ 13,203	$ 14,012
Gross amounts offset	(222)	(314)
Net amounts presented in the Consolidated Balance Sheets	12,981	13,698
Net Amount	12,981	13,698
Gross amounts recognized	13,175	13,961
Gross amounts offset	(222)	(314)
Net amounts presented in the Consolidated Balance Sheets	12,953	13,647
Gross amounts not offset	(12,059)	(12,611)
Net Amount	$ 894	$ 1,036