Commitments, Contingencies and Off-Balance Sheet Arrangements - Off-Balance Sheet Commitments (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($)
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - 2016	$ 16.2
Amount of Commitment Expiration by Period - 2017	18.2
Amount of Commitment Expiration by Period - 2018	0.4
Amount of Commitment Expiration by Period - 2019	1.9
Amount of Commitment Expiration by Period - 2020	0.4
Amount of Commitment Expiration by Period - Thereafter	25.7
Total Amounts Committed	62.8
Letters of Credit [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - Thereafter	21.5
Total Amounts Committed	21.5
Financial Guarantees [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - 2016	0.4
Amount of Commitment Expiration by Period - 2017	0.4
Amount of Commitment Expiration by Period - 2018	0.4
Amount of Commitment Expiration by Period - 2019	0.4
Amount of Commitment Expiration by Period - 2020	0.4
Amount of Commitment Expiration by Period - Thereafter	2.8
Total Amounts Committed	4.8
Funding Commitments [Member]
Commitments Contingencies And Off Balance Sheet Arrangements [Line Items]
Amount of Commitment Expiration by Period - 2016	15.8
Amount of Commitment Expiration by Period - 2017	17.8
Amount of Commitment Expiration by Period - 2019	1.5
Amount of Commitment Expiration by Period - Thereafter	1.4
Total Amounts Committed	$ 36.5