Derivatives and Hedging Activities - Derivatives in Cash Flow Hedging Relationships (Details 2) (Cash flow hedging, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Effect of cash flow hedging derivative financial instruments on other comprehensive income
Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income (Effective Portion)	$ 539	$ 1,600
Interest revenue
Effect of cash flow hedging derivative financial instruments on other comprehensive income
Location of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income	Interest revenue	Interest revenue
Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income (Effective Portion)	538	1,519
Other income
Effect of cash flow hedging derivative financial instruments on other comprehensive income
Location of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income	Other income	Other income
Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Income (Effective Portion)	1	81
Interest rate products
Effect of cash flow hedging derivative financial instruments on other comprehensive income
Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivative (Effective Portion)	$ 430