Derivative Instruments - Foreign Currency Derivative Contracts Outstanding (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Derivatives, Fair Value [Line Items]
Average rate	2.77
Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | AUD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	$ 692
Average rate	0.97
Expected hedge ratio	0.00%
Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | NZD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	86
Average rate	0.80
Expected hedge ratio	0.00%
Expected Maturity Date Year 2014 [Member]
Derivatives, Fair Value [Line Items]
Average rate	2.85
Expected Maturity Date Year 2014 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | AUD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	153
Average rate	0.99
Expected hedge ratio	19.00%
Expected Maturity Date Year 2014 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | NZD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	32
Average rate	0.80
Expected hedge ratio	62.00%
Expected Maturity Date Year 2015 [Member]
Derivatives, Fair Value [Line Items]
Average rate	2.78
Expected Maturity Date Year 2015 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | AUD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	270
Average rate	0.98
Expected hedge ratio	18.00%
Expected Maturity Date Year 2015 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | NZD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	47
Average rate	0.80
Expected hedge ratio	38.00%
Expected Maturity Date Year 2016 [Member]
Derivatives, Fair Value [Line Items]
Average rate	2.69
Expected Maturity Date Year 2016 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | AUD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	158
Average rate	0.95
Expected hedge ratio	11.00%
Expected Maturity Date Year 2016 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | NZD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	7
Average rate	0.81
Expected hedge ratio	14.00%
Expected Maturity Date Year 2017 [Member]
Derivatives, Fair Value [Line Items]
Average rate	2.67
Expected Maturity Date Year 2017 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | AUD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	105
Average rate	0.93
Expected hedge ratio	7.00%
Expected Maturity Date Year 2017 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | NZD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	0
Average rate	0.00
Expected hedge ratio	0.00%
Expected Maturity Date Year 2018 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | AUD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	6
Average rate	0.92
Expected hedge ratio	4.00%
Expected Maturity Date Year 2018 [Member] | Cash Flow Hedging [Member] | Foreign Currency Exchange Contracts [Member] | NZD [Member]
Derivatives, Fair Value [Line Items]
Derivative notional amount	$ 0
Average rate	0.00
Expected hedge ratio	0.00%