Schedule I - Condensed Financial Information of the Registrant - Condensed Statements of Cash Flows (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities
Net cash provided by operating activities	$ 1,088.6	$ 1,185.3	$ 1,174.9
Cash flows from investing activities
Purchases of property and equipment	(80.2)	(60.9)	(52.8)
Purchases of non-settlement related investments	(100.0)	0	0
Net cash used in investing activities	(341.3)	(258.2)	(1,360.3)
Cash flows from financing activities
Net proceeds from issuance of borrowings	497.3	742.8	696.3
Principal payments on borrowings	(300.0)	0	(696.3)
Net (repayments of)/proceeds from commercial paper	0	(297.0)	297.0
Proceeds from exercise of options	28.9	53.4	100.0
Cash dividends paid	(277.2)	(254.2)	(194.2)
Common stock repurchased	(399.7)	(766.5)	(803.9)
Net cash used in financing activities	(450.7)	(521.5)	(601.1)
Net change in cash and cash equivalents	296.6	405.6	(786.5)
Cash and cash equivalents at beginning of year	1,776.5	1,370.9	2,157.4
Cash and cash equivalents at end of year	2,073.1	1,776.5	1,370.9
Parent Company [Member]
Cash flows from operating activities
Net cash provided by operating activities	689.1	228.3	698.1
Cash flows from investing activities
Purchases of property and equipment	(8.5)	(3.3)	(4.2)
Purchases of non-settlement related investments	(100.0)	0	0
Net cash used in investing activities	(108.5)	(3.3)	(4.2)
Cash flows from financing activities
Advances from/(to) subsidiaries, net	(362.2)	679.1	(180.9)
Net proceeds from issuance of borrowings	497.3	742.8	696.3
Principal payments on borrowings	(300.0)	0	(696.3)
Net (repayments of)/proceeds from commercial paper	0	(297.0)	297.0
Proceeds from exercise of options	28.9	53.4	100.0
Cash dividends paid	(277.2)	(254.2)	(194.2)
Common stock repurchased	(399.7)	(766.5)	(803.9)
Net cash used in financing activities	(812.9)	157.6	(782.0)
Net change in cash and cash equivalents	(232.3)	382.6	(88.1)
Cash and cash equivalents at beginning of year	383.7	1.1	89.2
Cash and cash equivalents at end of year	$ 151.4	$ 383.7	$ 1.1