Investments - Schedule of Reconciliation of Minority Partner's Ownership Interest, Reported as Noncontrolling Interest (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Schedule of Equity Method Investments [Line Items]
Noncontrolling interest - beginning of period	$ 74.8
Net income attributable to noncontrolling interest	0.3	$ 1.8
Other comprehensive income attributable to noncontrolling interest	(1.9)	(1.3)
Noncontrolling interest - end of period	77.0
TCI [Member]
Schedule of Equity Method Investments [Line Items]
Noncontrolling interest - beginning of period	74.8	107.9
Net income attributable to noncontrolling interest	0.3	1.8
Other comprehensive income attributable to noncontrolling interest	1.9	1.3
Other		(0.1)
Noncontrolling interest - end of period	$ 77.0	$ 110.9