Summary of Significant Accounting Policies - Amortization of Intangible Assets Over Estimated Useful Lives (Detail)
12 Months Ended
Dec. 31, 2013
Maximum [Member] | Customer Relationships [Member]
 
Finite-Lived Intangible Assets [Line Items]  
Useful life of intangible assets 25 years
Maximum [Member] | Customer Loyalty Payments [Member]
 
Finite-Lived Intangible Assets [Line Items]  
Useful life of intangible assets 7 years
Minimum [Member] | Customer Relationships [Member]
 
Finite-Lived Intangible Assets [Line Items]  
Useful life of intangible assets 5 years
Minimum [Member] | Customer Loyalty Payments [Member]
 
Finite-Lived Intangible Assets [Line Items]  
Useful life of intangible assets 3 years