Derivatives and Hedging Activities - Other derivatives not accounted for as hedges (Details 3) (Derivatives not accounted for hedges, Other fee revenue, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Derivatives not accounted for hedges | Other fee revenue
Derivative Instruments, Gain (Loss) [Line Items]
Location of Gain (Loss) Recognized in Income on Derivative	Other fee revenue	Other fee revenue
Amount of Gain (Loss) Recognized in Income on Customer Derivatives	$ 252	$ 69