Derivative Financial Instruments - Additional Information (Detail) $ in Thousands	Sep. 30, 2015 USD ($)
Nondesignated
Derivative Instruments, Gain (Loss) [Line Items]
Derivative financial instruments held, notional amount	$ 2,469,634

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant