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Income Taxes - Additional Information (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income Tax Disclosure [Abstract]      
Provision for income taxes        
Increase (decrease) in valuation allowance 1.0 (0.3)  
Valuation allowance for operating loss and tax credit carryforwards 0 1.2  
Net operating loss carryforwards 79    
Capital loss carryforwards $ 0.3    
Capital loss carryforwards expiration period 2014    
Capital loss carryforwards expiration period start 2018    
Capital loss carryforwards expiration period end 2033    
Period for suspension of net operating loss carryforwards     4 years
Extension of the term of net loss carryforwards     4 years