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Debt - Senior Unsecured Notes Due 2016 - Additional Information (Detail) - Senior Unsecured Notes Due 2016 [Member] - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2006
Debt Instrument [Line Items]    
Senior unsecured notes, value of offering   $ 125.0
Credit facilities, periodic payments of interest   $ 65.0
Senior notes frequency of periodic payment Quarterly  
Unsecured senior notes, year of maturity   2016-07
London Interbank Offered Rate [Member]    
Debt Instrument [Line Items]    
Debt instrument, basis spread of interest rate   2.30%