Difference Between Statutory Federal Income Tax Rate and Effective Income Rate (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of Statutory Federal Tax Rate [Line Items]
Statutory tax rate	35.00%	35.00%	35.00%
State income taxes	3.70%	2.50%	2.50%
Permanent differences	(1.50%)	(0.20%)	(0.10%)
Other, net	(0.60%)	(0.30%)	(0.60%)
Effective tax rate	36.60%	37.00%	36.80%