Subsequent Events (Details)	12 Months Ended
Dec. 31, 2012 USD ($)	Dec. 31, 2012 VEB	Jun. 09, 2010 VEB	Apr. 02, 2010 VEB	Feb. 13, 2013 Subsequent Event [Member] USD ($)
Subsequent Event [Line Items]
Exchange rate, currency translation		4.30	6.88	2.60	$ 6.3
Expected one time non-recurring pre-tax charge in Q1/2013	$ 42,000,000

Expected Non-recurring Pre-tax Charge, Foreign Currency Translation Adjustment

No definition available.

Name:	bgc_ExpectedNonRecurringPreTaxChargeForeignCurrencyTranslationAdjustment
Namespace Prefix:	bgc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration