Investments - Schedule of Reconciliation of Minority Partner's Ownership Interest, Reported as Noncontrolling Interest (Detail) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2016 |
Jun. 30, 2015 |
Jun. 30, 2016 |
Jun. 30, 2015 |
|
| Schedule of Equity Method Investments [Line Items] | ||||
| Noncontrolling interest - beginning of period | $ 74.8 | |||
| Net income attributable to noncontrolling interest | $ 0.5 | $ 1.3 | 0.8 | $ 3.1 |
| Other comprehensive income attributable to noncontrolling interest | (0.1) | (1.7) | (2.0) | (3.0) |
| Distribution to noncontrolling interest | (7.1) | (8.4) | ||
| Noncontrolling interest - end of period | 70.5 | 70.5 | ||
| TCI [Member] | ||||
| Schedule of Equity Method Investments [Line Items] | ||||
| Noncontrolling interest - beginning of period | 74.8 | 107.9 | ||
| Net income attributable to noncontrolling interest | 0.8 | 3.1 | ||
| Other comprehensive income attributable to noncontrolling interest | 2.0 | 3.0 | ||
| Distribution to noncontrolling interest | (7.1) | (8.4) | ||
| Other | (0.1) | |||
| Noncontrolling interest - end of period | $ 70.5 | $ 105.5 | $ 70.5 | $ 105.5 |