Effective Tax Rate Differs from Statutory United States Federal Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Effective Tax Rate Differs From Statutory United States Federal Income Tax Rate [Abstract]
Statutory Rate	35.00%	35.00%	35.00%
Increases in United States Federal Taxes
State Income Taxes, Net of Federal Income Tax Benefit	3.10%	2.50%	2.70%
Effective Income Tax Rate Reconciliation, Tax Credits, Other	(1.70%)	(0.10%)	(0.30%)
Other, Net	(1.60%)	0.10%	0.60%
Effective Tax Rate	34.80%	37.50%	38.00%