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 |