Income Taxes- Reconciliation of Statutory Federal Income Tax Rate to Effective Income Tax Rate (Detail)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Income Tax Disclosure [Abstract]
Federal rate (percent)	35.00%	35.00%
State and local income taxes, net of federal income tax benefit (percent)	1.70%	3.10%
Tax-exempt income (percent)	(3.00%)	(2.10%)
Foreign operations (percent)	(5.00%)	(4.40%)
Tax credits (percent)	(5.50%)	(2.70%)
Effective Income Tax Rate Reconciliation, Tax Litigation	105.60%	0.00%
Other – net (percent)	0.50%	(0.20%)
Effective rate (percent)	129.30%	28.70%