Derivative Instruments and Hedging Activities (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivative Assets
Gross amounts of recognized assets	$ 13,792	$ 54,454
Gross amounts offset in the statement of financial position	(10,773)	(3,630)
Net amounts of assets presented in the statement of financial position	3,019	50,824
Gross amounts financial instrument not offset in the statement of financial position	373	1,892
Net amount	3,392	52,716
Derivative Liabilities
Gross amounts of recognized liabilities	24,685	3,822
Gross amounts offset in the statement of financial position	(10,773)	(3,630)
Net amounts of liabilities presented in the statement of financial position	13,912	192
Net amount	$ 13,912	$ 192