Accumulated Other Comprehensive Income (Loss) Changes During Period (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
TAX EFFECT
Other comprehensive income (loss), after reclassifications	$ (72.4)	$ (17.0)	$ (18.6)
AFTER TAX
Other Comprehensive Income (Loss)	2.7	(53.0)	(75.4)
Noncredit-Related Unrealized Losses on Securities OTTI
BEFORE TAX
Other comprehensive income (loss) before reclassifications	0.0	0.0	4.5
TAX EFFECT
Other comprehensive income (loss) before reclassifications	0.0	0.0	(1.7)
AFTER TAX
Other comprehensive income (loss) before reclassifications	0.0	0.0	2.8
Other Unrealized (Losses) Gains on Securities Available for Sale
BEFORE TAX
Other comprehensive income (loss) before reclassifications	(1.8)	(94.3)	30.1
TAX EFFECT
Other comprehensive income (loss) before reclassifications	0.7	35.5	(11.4)
AFTER TAX
Other comprehensive income (loss) before reclassifications	(1.1)	(58.8)	18.7
Net Unrealized (Losses) Gains on Securities Available for Sale
BEFORE TAX
Reclassification adjustments	(0.5)	0.3	0.1
Other comprehensive income (loss), after reclassifications	(2.3)	(94.0)	34.7
TAX EFFECT
Reclassification adjustments	0.2	(0.1)	0.0
Other comprehensive income (loss), after reclassifications	0.9	35.4	(13.1)
AFTER TAX
Reclassification adjustments	(0.3)	0.2	0.1
Other Comprehensive Income (Loss)	(1.4)	(58.6)	21.6
Net Unrealized Gains (Losses) on Cash Flow Hedges
BEFORE TAX
Other comprehensive income (loss) before reclassifications	4.4	(1.2)	(8.7)
Reclassification adjustments	(1.9)	4.7	(4.0)
Other comprehensive income (loss), after reclassifications	2.5	3.5	(12.7)
TAX EFFECT
Other comprehensive income (loss) before reclassifications	5.9	0.2	3.6
Reclassification adjustments	0.7	(2.0)	1.5
Other comprehensive income (loss), after reclassifications	6.6	(1.8)	5.1
AFTER TAX
Other comprehensive income (loss) before reclassifications	10.3	(1.0)	(5.1)
Reclassification adjustments	(1.2)	2.7	(2.5)
Other Comprehensive Income (Loss)	9.1	1.7	(7.6)
Net Foreign Currency Adjustments
BEFORE TAX
Other comprehensive income (loss) before reclassifications	(126.5)	(101.5)	(107.8)
Other comprehensive income (loss), after reclassifications	80.6	28.4	33.8
TAX EFFECT
Other comprehensive income (loss) before reclassifications	(3.1)	4.9	10.8
Other comprehensive income (loss), after reclassifications	(81.5)	(44.3)	(42.6)
AFTER TAX
Other comprehensive income (loss) before reclassifications	(129.6)	(96.6)	(97.0)
Other Comprehensive Income (Loss)	(0.9)	(15.9)	(8.8)
Long-Term Intra-Entity Foreign Currency Transaction Losses
BEFORE TAX
Other comprehensive income (loss) before reclassifications	(5.3)	(18.7)	(1.0)
TAX EFFECT
Other comprehensive income (loss) before reclassifications	2.0	7.1	0.4
AFTER TAX
Other comprehensive income (loss) before reclassifications	(3.3)	(11.6)	(0.6)
Net Investment Hedge Gains (Losses)
BEFORE TAX
Other comprehensive income (loss) before reclassifications	212.4	148.6	142.6
TAX EFFECT
Other comprehensive income (loss) before reclassifications	(80.4)	(56.3)	(53.8)
AFTER TAX
Other comprehensive income (loss) before reclassifications	132.0	92.3	88.8
Net Pension and Other Postretirement Benefit Adjustments
BEFORE TAX
Other comprehensive income (loss) before reclassifications	(31.1)	(12.2)	(137.8)
Reclassification adjustments	25.4	38.3	25.2
Other comprehensive income (loss), after reclassifications	(5.7)	26.1	(112.6)
TAX EFFECT
Other comprehensive income (loss) before reclassifications	11.2	8.2	41.5
Reclassification adjustments	(9.6)	(14.5)	(9.5)
Other comprehensive income (loss), after reclassifications	1.6	(6.3)	32.0
AFTER TAX
Other comprehensive income (loss) before reclassifications	(19.9)	(4.0)	(96.3)
Reclassification adjustments	15.8	23.8	15.7
Other Comprehensive Income (Loss)	$ (4.1)	$ 19.8	$ (80.6)