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Reconciliation of Effective Tax Rate to Federal Statutory Tax Rate (Detail)
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Income Tax Disclosure [Abstract]      
U.S. federal statutory rate 35.00% 35.00% 35.00%
State taxes, net of federal benefit 3.20% 2.90% 3.00%
State incentives (0.60%)    
State law changes 0.10% 0.30% (0.20%)
Nondeductible expenses 0.80% 0.50% 0.60%
Provision for valuation allowance     (0.30%)
Other 0.10% 0.20% 0.20%
Net effective rate 38.60% 38.90% 38.30%