Actual Income Tax Expense Differs from Expected Amounts Computed by Applying U.S. Federal Income Tax Rate to Earnings Before Income Taxes (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Increase (decrease) in taxes resulting from:
Expected income tax expense at statutory rate	$ 64,703	$ 62,910	$ 221,429
Domestic production activities	(3,150)	(2,450)	(2,625)
Income Tax Reconciliation, Statutory Expirations of Unrecognized Tax Benefits	(7,862)	(477)	(100)
State and local income taxes, net of federal benefit	9,293	4,766	22,275
Income Tax Reconciliation, Other Reconciling Items	2,897	1,565	6,271
Income tax expense	$ 65,881	$ 66,314	$ 247,250