Long-Term Debt - Additional Information (Detail) (Parent company, USD $)	3 Months Ended
	Mar. 31, 2014
Senior Debt Obligations | Fixed Rate 2.30 Percent Notes Due 2019
Debt Instrument
Issue of senior notes to third party investors	$ 500,000,000
Maturity date(s) Start	Feb. 28, 2014
Maturity date(s) End	Mar. 01, 2019
Variable Interest Entity, Primary Beneficiary | Automobile Loan
Debt Instrument
Other Long Term Debt	$ 1,300,000,000