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Derivative Instruments and Hedging Activities - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Derivative [Line Items]    
Derivative instruments not designated as hedging instruments, liability $ 23.0  
Aggregate fair value of net liability position 3.6  
CME    
Derivative [Line Items]    
Collateral posted with counterparties, net of CME variation margin 34.1  
Interest Rate Swaps    
Derivative [Line Items]    
Accumulated net after-tax losses related to effective cash flow hedges 18.5 $ 12.5
Estimated amount of interest rate derivatives to be reclassified to interest expense 7.4  
Derivatives designated as hedging instruments: | Cash Flow Hedge | Interest Rate Caps and Swaps | CME    
Derivative [Line Items]    
CME variation margins 13.5  
Derivatives not designated as hedging instruments: | Interest Rate Swaps | CME    
Derivative [Line Items]    
CME variation margins $ 3.1