Accumulated Other Comprehensive Income (Loss) (Details of Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
After Tax
Other Comprehensive Income (Loss)	$ (20.1)	$ 0.0	$ 113.0	$ 46.0
Noncredit-Related Unrealized Losses on Securities OTTI
Before Tax
Other comprehensive income (loss), before reclassifications, before tax	0.0	0.0	0.0	0.0
Tax Effect
Other comprehensive income (loss), before reclassifications, tax	0.0	0.0	0.0	0.0
After Tax
Other comprehensive income (loss), before reclassification, after tax	0.0	0.0	0.0	0.0
Other Unrealized Gains (Losses) on Securities Available for Sale
Before Tax
Other comprehensive income (loss), before reclassifications, before tax	(22.3)	(11.0)	152.1	39.4
Tax Effect
Other comprehensive income (loss), before reclassifications, tax	8.4	4.0	(57.6)	(14.9)
After Tax
Other comprehensive income (loss), before reclassification, after tax	(13.9)	(7.0)	94.6	24.5
Net Unrealized Gains (Losses) on Securities Available for Sale
Before Tax
Reclassification Adjustment for (Gains) Losses Included in Net Income	(0.2)	0.0	(0.5)	0.3
Net Change	(22.5)	(11.0)	151.6	39.7
Tax Effect
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.2	0.0	0.2	(0.1)
Net Change	8.6	4.0	(57.4)	(15.0)
After Tax
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0	0.0	(0.3)	0.2
Other Comprehensive Income (Loss)	(13.9)	(7.0)	94.3	24.7
Net Unrealized Gains (Losses) on Cash Flow Hedges
Before Tax
Other comprehensive income (loss), before reclassifications, before tax	(6.3)	6.4	3.7	6.5
Reclassification Adjustment for (Gains) Losses Included in Net Income	4.6	0.1	5.2	2.4
Net Change	(1.7)	6.5	8.9	8.9
Tax Effect
Other comprehensive income (loss), before reclassifications, tax	3.5	(3.3)	(0.3)	(2.7)
Reclassification Adjustment for (Gains) Losses Included in Net Income	(1.7)	0.0	(2.0)	(0.9)
Net Change	1.8	(3.3)	(2.3)	(3.6)
After Tax
Other comprehensive income (loss), before reclassification, after tax	(2.8)	3.1	3.4	3.8
Reclassification Adjustment for (Gains) Losses Included in Net Income	2.9	0.1	3.2	1.5
Other Comprehensive Income (Loss)	0.1	3.2	6.6	5.3
Net Foreign Currency Adjustments
Before Tax
Other comprehensive income (loss), before reclassifications, before tax	(11.7)	(32.6)	(52.7)	(69.7)
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0	0.0	0.0	0.0
Net Change	(6.8)	16.2	36.9	15.1
Tax Effect
Other comprehensive income (loss), before reclassifications, tax	(0.9)	0.0	(2.3)	14.6
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0	0.0	0.0	0.0
Net Change	(2.7)	(18.5)	(36.2)	(17.5)
After Tax
Other comprehensive income (loss), before reclassification, after tax	(12.6)	(32.6)	(55.0)	(55.1)
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0	0.0	0.0	0.0
Other Comprehensive Income (Loss)	(9.5)	(2.3)	0.7	(2.4)
Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses)
Before Tax
Other comprehensive income (loss), before reclassifications, before tax	0.8	(0.3)	2.0	0.2
Tax Effect
Other comprehensive income (loss), before reclassifications, tax	(0.3)	0.1	(0.8)	(0.1)
After Tax
Other comprehensive income (loss), before reclassification, after tax	0.5	(0.2)	1.2	0.1
Net Investment Hedge Gains (Losses)
Before Tax
Other comprehensive income (loss), before reclassifications, before tax	4.1	49.1	87.6	84.6
Tax Effect
Other comprehensive income (loss), before reclassifications, tax	(1.5)	(18.6)	(33.1)	(32.0)
After Tax
Other comprehensive income (loss), before reclassification, after tax	2.6	30.5	54.5	52.6
Net Pension and Other Postretirement Benefit Adjustments
Before Tax
Other comprehensive income (loss), before reclassifications, before tax	0.0	0.0	0.0	0.0
Reclassification Adjustment for (Gains) Losses Included in Net Income	6.3	9.6	19.1	28.8
Net Change	6.3	9.6	19.1	28.8
Tax Effect
Other comprehensive income (loss), before reclassifications, tax	0.0	0.0	0.0	0.0
Reclassification Adjustment for (Gains) Losses Included in Net Income	(3.0)	(3.5)	(7.7)	(10.4)
Net Change	(3.0)	(3.5)	(7.7)	(10.4)
After Tax
Other comprehensive income (loss), before reclassification, after tax	0.0	0.0	0.0	0.0
Reclassification Adjustment for (Gains) Losses Included in Net Income	3.3	6.1	11.4	18.4
Other Comprehensive Income (Loss)	$ 3.3	$ 6.1	$ 11.4	$ 18.4