Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income	[1]	$ 1,697	$ 1,360	$ 4,816	$ 4,365
Class A common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation (A)	[1]	$ 1,358	$ 1,076	$ 3,850	$ 3,458
Weighted- Average Shares Outstanding (B)		1,955	1,982	1,964	2,001
Earnings per Share (A)/(B)	[2]	$ 0.69	$ 0.54	$ 1.96	$ 1.73
Income Allocation (A)	[1]	$ 1,697	$ 1,360	$ 4,816	$ 4,365
Weighted- Average Shares Outstanding (B)	[3]	2,448	2,511	2,462	2,533
Earnings per Share (A)/(B)	[2]	$ 0.69	$ 0.54	$ 1.96	$ 1.72
Class B common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation (A)	[1]	$ 281	$ 224	$ 793	$ 714
Weighted- Average Shares Outstanding (B)	[4]	245	245	245	245
Earnings per Share (A)/(B)	[2]	$ 1.14	$ 0.91	$ 3.23	$ 2.91
Income Allocation (A)	[1]	$ 281	$ 224	$ 792	$ 712
Weighted- Average Shares Outstanding (B)	[4]	245	245	245	245
Earnings per Share (A)/(B)	[2]	$ 1.14	$ 0.91	$ 3.22	$ 2.90
Class C common stock
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation (A)	[1]	$ 54	$ 56	$ 161	$ 180
Weighted- Average Shares Outstanding (B)	[4]	20	26	21	26
Earnings per Share (A)/(B)	[2]	$ 2.78	$ 2.17	$ 7.84	$ 6.91
Income Allocation (A)	[1]	$ 54	$ 56	$ 161	$ 180
Weighted- Average Shares Outstanding (B)	[4]	20	26	21	26
Earnings per Share (A)/(B)	[2]	$ 2.77	$ 2.17	$ 7.82	$ 6.89
Participating securities
Schedule of Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income Allocation (A)	[1],[5]	$ 4	$ 4	$ 12	$ 13
Income Allocation (A)	[1],[5]	$ 4	$ 4	$ 12	$ 13

[1] Net income is allocated based on proportional ownership on an as-converted basis. The weighted-average number of shares of as-converted class B common stock used in the income allocation was 405 million for the three and nine months ended June 30, 2015, and 413 million for the three and nine months ended June 30, 2014. The weighted-average number of shares of as-converted class C common stock used in the income allocation was 78 million and 82 million for the three and nine months ended June 30, 2015, respectively, and 103 million and 104 million for the three and nine months ended June 30, 2014, respectively.

[2] Figures in the table may not recalculate exactly due to rounding. Earnings per share is calculated based on unrounded numbers. The number of shares and per share amounts for the prior periods presented have been retroactively adjusted to reflect the four-for-one stock split effected in the fiscal second quarter of 2015. See Note 9—Stockholders' Equity.

[3] Weighted-average diluted shares outstanding are calculated on an as-converted basis, and include incremental common stock equivalents, as calculated under the treasury stock method. The computation includes approximately 5 million common stock equivalents for the three and nine months ended June 30, 2015, and 6 million and 7 million common stock equivalents for the three and nine months ended June 30, 2014, respectively, because their effect would be dilutive. The calculation excludes 1 million of common stock equivalents for the three months ended June 30, 2015 and 2014, and 2 million of common stock equivalents for the nine months ended June 30, 2015 and 2014, because their effect would have been anti-dilutive.

[4] The outstanding number of shares of class B and C common stock were not impacted by the stock split as these stockholders received an adjustment to their respective conversion ratios instead of stock dividends. See Note 9—Stockholders' Equity. Weighted-average basic and diluted shares outstanding for class B and C common stock are calculated based on the common shares outstanding of each respective class rather than on an as-converted basis.

[5] Participating securities are unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents, such as the Company's restricted stock awards, restricted stock units and earned performance-based shares.