Accumulated Other Comprehensive Income (Loss) Changes During Period (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss)	$ (13.2)	$ 12.8	$ 25.9	$ (54.9)
Net Unrealized Gains (Losses) on Securities Available for Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	(9.0)	9.4	51.9	(119.2)
Tax Effect	3.3	(3.6)	(19.6)	44.8
Other Comprehensive Income (Loss)	(5.7)	5.8	32.3	(74.4)
Net Unrealized Gains (Losses) on Securities Available for Sale | Noncredit-Related Unrealized Losses on Securities OTTI
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	5.5		3.7	2.1
Tax Effect	(2.1)		(1.4)	(0.8)
Other Comprehensive Income (Loss)	3.4		2.3	1.3
Net Unrealized Gains (Losses) on Securities Available for Sale | Other Unrealized Gains (Losses) on Securities Available-for-Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	(14.2)	7.3	48.8	(123.2)
Tax Effect	5.4	(2.8)	(18.2)	46.3
Other Comprehensive Income (Loss)	(8.8)	4.5	30.6	(76.9)
Net Unrealized Gains (Losses) on Securities Available for Sale | Reclassification Adjustment for (Gains) Losses Included in Net Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	(0.3)	2.1	(0.6)	1.9
Tax Effect		(0.8)		(0.7)
Other Comprehensive Income (Loss)	(0.3)	1.3	(0.6)	1.2
Net Unrealized Gains (Losses) on Cash Flow Hedge Designations
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	(11.3)	6.4	(9.8)	1.7
Tax Effect	3.9	(2.1)	3.4	(0.5)
Other Comprehensive Income (Loss)	(7.4)	4.3	(6.4)	1.2
Net Unrealized Gains (Losses) on Cash Flow Hedge Designations | Reclassification Adjustment for (Gains) Losses Included in Net Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	(3.7)	1.1	(3.3)	5.7
Tax Effect	1.4	(0.4)	1.2	(2.1)
Other Comprehensive Income (Loss)	(2.3)	0.7	(2.1)	3.6
Net Unrealized Gains (Losses) on Cash Flow Hedge Designations | Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	(7.6)	5.3	(6.5)	(4.0)
Tax Effect	2.5	(1.7)	2.2	1.6
Other Comprehensive Income (Loss)	(5.1)	3.6	(4.3)	(2.4)
Net Foreign Currency Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	35.4	(33.8)	13.5	(4.0)
Tax Effect	(39.0)	29.4	(24.0)	1.2
Other Comprehensive Income (Loss)	(3.6)	(4.4)	(10.5)	(2.8)
Net Foreign Currency Adjustments | Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	(77.1)	55.0	(57.2)	5.3
Tax Effect	6.6	(4.0)	6.0	(2.3)
Other Comprehensive Income (Loss)	(70.5)	51.0	(51.2)	3.0
Net Foreign Currency Adjustments | Net Investment Hedge Gains (Losses)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	119.9	(88.8)	79.7	(9.3)
Tax Effect	(45.6)	33.4	(30.0)	3.5
Other Comprehensive Income (Loss)	74.3	(55.4)	49.7	(5.8)
Net Foreign Currency Adjustments | Long Term Intra Entity Foreign Currency Transaction Losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	(7.4)		(9.0)
Other Comprehensive Income (Loss)	(7.4)		(9.0)
Net Pension and Other Postretirement Benefit Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	6.5	11.3	19.0	33.7
Tax Effect	(3.0)	(4.2)	(8.5)	(12.6)
Other Comprehensive Income (Loss)	3.5	7.1	10.5	21.1
Net Pension and Other Postretirement Benefit Adjustments | Reclassification Adjustment for (Gains) Losses Included in Net Income
Accumulated Other Comprehensive Income (Loss) [Line Items]
Before Tax	6.5	11.3	19.0	33.7
Tax Effect	(3.0)	(4.2)	(8.5)	(12.6)
Other Comprehensive Income (Loss)	$ 3.5	$ 7.1	$ 10.5	$ 21.1