CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions		3 Months Ended			6 Months Ended
		Mar. 31, 2017	Mar. 31, 2016		Mar. 31, 2017		Mar. 31, 2016
Operating Revenues
Service revenues		$ 1,993	$ 1,699		$ 3,911		$ 3,344
Data processing revenues		1,843	1,473		3,735		2,952
International transaction revenues		1,469	1,045		2,958		2,076
Other revenues		203	198		406		396
Client incentives		(1,031)	(789)		(2,072)		(1,577)
Net operating revenues		4,477	3,626		8,938		7,191
Operating Expenses
Personnel		704	528		1,275		1,027
Marketing		193	186		411		380
Network and processing		150	126		295		254
Professional fees		83	66		163		138
Depreciation and amortization		131	121		277		241
General and administrative		406	164		592		320
Litigation provision (Note 13)		2	1		17		1
Total operating expenses		1,669	1,192		3,030		2,361
Operating income		2,808	2,434		5,908		4,830
Non-operating (Expense) Income
Interest expense		(135)	(132)		(275)		(161)
Other		29	139		48		411
Non-operating (expense) income		(106)	7		(227)		250
Income before income taxes		2,702	2,441		5,681		5,080
Income tax provision (Note 12)		2,272	734		3,181		1,432
Net income		$ 430	$ 1,707		$ 2,500		$ 3,648
Class A common stock
Earnings Per Share
Basic earnings per share (in dollars per share)		$ 0.18	$ 0.71	[1]	$ 1.04	[1]	$ 1.51	[1]
Basic weighted-average shares outstanding (in shares)		1,854	1,909		1,857		1,923
Diluted earnings per share (in dollars per share)		$ 0.18	$ 0.71	[1]	$ 1.04	[1]	$ 1.51	[1]
Diluted weighted-average shares outstanding (in shares)	[2]	2,406	2,401		2,413		2,416
Class B common stock
Earnings Per Share
Basic earnings per share (in dollars per share)		$ 0.30	$ 1.17	[1]	$ 1.71	[1]	$ 2.49	[1]
Basic weighted-average shares outstanding (in shares)		245	245		245		245
Diluted earnings per share (in dollars per share)		$ 0.29	$ 1.17	[1]	$ 1.71	[1]	$ 2.49	[1]
Diluted weighted-average shares outstanding (in shares)		245	245		245		245
Class C common stock
Earnings Per Share
Basic earnings per share (in dollars per share)		$ 0.72	$ 2.85	[1]	$ 4.15	[1]	$ 6.05	[1]
Basic weighted-average shares outstanding (in shares)		15	19		16		19
Diluted earnings per share (in dollars per share)		$ 0.72	$ 2.84	[1]	$ 4.14	[1]	$ 6.04	[1]
Diluted weighted-average shares outstanding (in shares)		15	19		16		19

[1] Figures in the table may not recalculate exactly due to rounding. Earnings per share is calculated based on unrounded numbers.

[2] 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 six months ended March 31, 2017 and 2016, because their effect would be dilutive. The computation excludes 3 million of common stock equivalents for the three and six months ended March 31, 2017 and 1 million of common stock equivalents for the three and six months ended March 31, 2016, because their effect would have been anti-dilutive.