Income Taxes (Details)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Income Tax Disclosure [Abstract]
New York City unincorporated business tax (in hundredths)	4.00%
Federal tax on partnership gross income (in hundredths)	3.50%
Income tax computation rate on ownership interest (in hundredths)	3.50%
Decrease in Holding's equity earnings (in hundredths)	(35.90%)
Holding's income tax decrease (in hundredths)	(18.60%)
Effective tax rate (in hundredths)	18.40%	14.50%