Notes Payable - Additional Information (Detail)	12 Months Ended				1 Months Ended		1 Months Ended		1 Months Ended			1 Months Ended			1 Months Ended			1 Months Ended			1 Months Ended				1 Months Ended		1 Months Ended	12 Months Ended			1 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)	Jul. 31, 2011 Yen Denominated Samurai Notes JPY (¥)	Jul. 31, 2011 1.47% yen-denominated Samurai notes due July 2014 JPY (¥)	Dec. 31, 2011 1.47% yen-denominated Samurai notes due July 2014 JPY (¥)	Jul. 31, 2011 1.84% yen-denominated Samurai notes due July 2016 JPY (¥)	Dec. 31, 2011 1.84% yen-denominated Samurai notes due July 2016 JPY (¥)	Jul. 31, 2011 Variable interest rate yen-denominated Samurai notes due July 2014 JPY (¥)	Dec. 31, 2011 Variable interest rate yen-denominated Samurai notes due July 2014 JPY (¥)	Dec. 31, 2010 Senior Notes USD ($)	Aug. 31, 2010 6.45% senior notes due August 2040 USD ($)	Dec. 31, 2011 6.45% senior notes due August 2040 USD ($)	Dec. 31, 2010 6.45% senior notes due August 2040 USD ($)	Aug. 31, 2010 3.45% senior notes due August 2015 USD ($)	Dec. 31, 2011 3.45% senior notes due August 2015	Dec. 31, 2010 3.45% senior notes due August 2015	Dec. 31, 2009 6.90% senior notes due December 2039 USD ($)	Dec. 31, 2011 6.90% senior notes due December 2039 USD ($)	Dec. 31, 2010 6.90% senior notes due December 2039 USD ($)	May 31, 2009 8.50% senior notes due May 2019 USD ($)	Dec. 31, 2011 8.50% senior notes due May 2019	Dec. 31, 2010 8.50% senior notes due May 2019	Sep. 30, 2006 Yen Denominated Uridashi Notes JPY (¥)	Sep. 30, 2006 1.52% yen-denominated Uridashi notes paid September 2011 JPY (¥)	Dec. 31, 2010 1.52% yen-denominated Uridashi notes paid September 2011 JPY (¥)	Sep. 30, 2006 2.26% yen-denominated Uridashi notes due September 2016 JPY (¥)	Dec. 31, 2009 2.26% yen-denominated Uridashi notes due September 2016 JPY (¥)	Dec. 31, 2011 2.26% yen-denominated Uridashi notes due September 2016 JPY (¥)	Dec. 31, 2010 2.26% yen-denominated Uridashi notes due September 2016 JPY (¥)	Sep. 30, 2006 Variable interest rate yen-denominated Uridashi notes paid September 2011 JPY (¥)	Dec. 31, 2010 Variable interest rate yen-denominated Uridashi notes paid September 2011 JPY (¥)	Jun. 30, 2007 1.87% yen-denominated Samurai notes due June 2012 JPY (¥)	Dec. 31, 2009 1.87% yen-denominated Samurai notes due June 2012 JPY (¥)	Dec. 31, 2011 1.87% yen-denominated Samurai notes due June 2012 JPY (¥)	Dec. 31, 2010 1.87% yen-denominated Samurai notes due June 2012 JPY (¥)
Debt Instrument [Line Items]
Notes payable, principal amount				¥ 50,000,000,000	¥ 28,700,000,000	¥ 28,700,000,000	¥ 15,800,000,000	¥ 15,800,000,000	¥ 5,500,000,000	¥ 5,500,000,000	$ 2,000,000,000	$ 450,000,000	$ 450,000,000	$ 450,000,000	$ 300,000,000			$ 400,000,000	$ 400,000,000	$ 400,000,000	$ 850,000,000			¥ 45,000,000,000	¥ 15,000,000,000	¥ 15,000,000,000	¥ 10,000,000,000		¥ 8,000,000,000	¥ 8,000,000,000	¥ 20,000,000,000	¥ 20,000,000,000	¥ 30,000,000,000		¥ 26,600,000,000	¥ 26,600,000,000
Notes payable, interest rate					1.47%	1.47%	1.84%	1.84%		1.34%			6.45%	6.45%		3.45%	3.45%		6.90%	6.90%		8.50%	8.50%			1.52%			2.26%	2.26%		0.66%			1.87%	1.87%
Maturity date					3 years		5 years		3 years			30 years			5 years			30 years			10 years				5 years		10 years				5 years		5 years
Notes payable, effective interest rate									1.475%	1.475%																						1.52%
Extinguishment of notes																												2,000,000,000						3,400,000,000
Principal payments under debt obligations																												1,400,000,000						2,500,000,000
Gain on extinguishment of debt	$ 0	$ 0	$ 16,000,000																									¥ 600,000,000						¥ 900,000,000