Stockholders' Equity - Changes in Each Component of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016		Sep. 30, 2017	Sep. 30, 2016		Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss		$ (82.1)			$ (82.1)				$ (92.0)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance					394.1	$ 405.6
Net current-period other comprehensive income (loss)		3.4	$ 0.4		9.9	10.1
Ending Balance		425.2	401.5		425.2	401.5
Actuarial Losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	[1]	(79.0)	(70.5)	[2]	(79.0)	(70.5)	[2]	$ (78.9)	(79.0)	$ (71.8)	$ (75.6)	[2]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive (loss) income before reclassifications	[1]	(0.7)	0.3		(1.6)	1.7	[2]
Amounts reclassified from accumulated other comprehensive loss	[1]	0.6	1.0		1.6	3.4	[2]
Net current-period other comprehensive income (loss)	[1]	(0.1)	1.3		0.0	5.1	[2]
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	[1]	(3.5)	(8.2)	[3]	(3.5)	(8.2)	[3]	(6.8)	(13.0)	(7.3)	(13.3)	[3]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive (loss) income before reclassifications	[1]	3.3	(0.9)		9.5	(2.3)	[3]
Amounts reclassified from accumulated other comprehensive loss	[1]	0.0	0.0		0.0	7.4	[3]
Net current-period other comprehensive income (loss)	[1]	3.3	(0.9)		9.5	5.1	[3]
Unrealized Gain on Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	[1]	0.4	0.0		0.4	0.0		0.2	0.0	0.0	0.1
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive (loss) income before reclassifications	[1]	0.2	0.0		0.4	0.0
Amounts reclassified from accumulated other comprehensive loss	[1]	0.0	0.0		0.0	(0.1)
Net current-period other comprehensive income (loss)	[1]	0.2	0.0		0.4	(0.1)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive loss	[1]	(82.1)	(78.7)		(82.1)	(78.7)		$ (85.5)	$ (92.0)	$ (79.1)	$ (88.8)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance					(92.0)	(88.8)
Other comprehensive (loss) income before reclassifications	[1]	2.8	(0.6)		8.3	(0.6)
Amounts reclassified from accumulated other comprehensive loss	[1]	0.6	1.0		1.6	10.7
Net current-period other comprehensive income (loss)	[1]	3.4	0.4		9.9	10.1
Ending Balance		$ (82.1)	$ (78.7)		$ (82.1)	(78.7)
Bronto
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Actuarial loss						0.4
Fire Rescue | Foreign Currency Translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Amounts reclassified from accumulated other comprehensive loss						$ 7.1

[1] Amounts in parentheses indicate debits.

[2] In connection with the sale of Bronto, the Company recognized an actuarial loss of $0.4 million attributable to Bronto’s defined benefit plan and included it in the calculation of the associated gain on disposal in the nine months ended September 30, 2016.

[3] The Company recognized a foreign currency translation loss of $7.1 million in the nine months ended September 30, 2016 in connection with the sale of Bronto. The recognition of the translation loss, which represented the cumulative translation effects attributable to the Fire Rescue Group, was included in Gain (loss) from discontinued operations and disposal for the applicable period.