Reconciliation of the Provision for Income Taxes using Statutory Federal Income Tax Rate to the Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Disclosure reconciliation of the provision for income taxes using statutory federal income tax rate to the effective income tax rate [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
State income taxes, net of federal benefit	2.70%	2.70%	2.70%
Other	0.30%	0.20%	0.30%
Effective Income Tax Rate, Continuing Operations, Total	38.00%	37.90%	38.00%