Changes in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL	$ (51.4)	$ (18.9)	$ (39.5)	$ (21.0)
Other comprehensive (loss) income before reclassifications	1.0		(11.7)	2.9
Amounts reclassified from AOCL	(0.9)	(0.9)	(1.8)	(2.0)
Income tax	0.8	0.7	2.5	1.0
Net current period other comprehensive (loss) income	0.9	(0.2)	(11.0)	1.9
Total AOCL	(50.5)	(19.1)	(50.5)	(19.1)
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL	(3.3)	1.2	(0.9)	1.1
Other comprehensive (loss) income before reclassifications	(0.9)	(0.9)	(4.7)	(0.7)
Income tax	0.4	0.3	1.8	0.2
Net current period other comprehensive (loss) income	(0.5)	(0.6)	(2.9)	(0.5)
Total AOCL	(3.8)	0.6	(3.8)	0.6
Accumulated Defined Benefit Plans Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL	(17.6)	(8.6)	(17.0)	(7.9)
Amounts reclassified from AOCL	(0.9)	(0.9)	(1.8)	(2.0)
Income tax	0.4	0.4	0.7	0.8
Net current period other comprehensive (loss) income	(0.5)	(0.5)	(1.1)	(1.2)
Total AOCL	(18.1)	(9.1)	(18.1)	(9.1)
Accumulated Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance of AOCL	(30.5)	(11.5)	(21.6)	(14.2)
Other comprehensive (loss) income before reclassifications	1.9	0.9	(7.0)	3.6
Net current period other comprehensive (loss) income	1.9	0.9	(7.0)	3.6
Total AOCL	$ (28.6)	$ (10.6)	$ (28.6)	$ (10.6)