Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Commitments and contingencies
Minimum possible ranges of losses in excess of any amounts accrued	$ 0
Maximum possible ranges of losses in excess of any amounts accrued	85
Patent infringement
Commitments and contingencies
Minimum possible ranges of losses in excess of any amounts accrued	0
Maximum possible ranges of losses in excess of any amounts accrued	6
Merchant matters
Commitments and contingencies
Minimum possible ranges of losses in excess of any amounts accrued	0
Maximum possible ranges of losses in excess of any amounts accrued	75
Other matters
Commitments and contingencies
Minimum possible ranges of losses in excess of any amounts accrued	0
Maximum possible ranges of losses in excess of any amounts accrued	$ 4