Derivative Instruments and Hedging Activities Schedule of Interest Rate Swaps Associated with Borrowings (Details) (Interest Rate Risk Associated with Borrowings [Member], Swap [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Derivative, Notional Amount	$ 14,625,000	$ 14,425,000
Derivative, Average Fixed Interest Rate	0.75%	0.698%
Derivative, Average Variable Interest Rate	0.236%	0.235%
Derivative, Weighted Average Remaining Maturity	2.471	2.501
Derivative Maturity Within One Year From Balance Sheet Date [Member]
Derivative [Line Items]
Derivative, Notional Amount	3,000,000	3,900,000
Derivative, Average Fixed Interest Rate	0.295%	0.30%
Derivative, Average Variable Interest Rate	0.234%	0.245%
Derivative, Weighted Average Remaining Maturity	.731	.764
Derivative Maturity Over One And Within Two Years From Balance Sheet Date [Member]
Derivative [Line Items]
Derivative, Notional Amount	1,000,000	1,000,000
Derivative, Average Fixed Interest Rate	0.383%	0.383%
Derivative, Average Variable Interest Rate	0.237%	0.244%
Derivative, Weighted Average Remaining Maturity	.794	1.044
Derivative Maturity Over Two And Within Three Years From Balance Sheet Date [Member]
Derivative [Line Items]
Derivative, Notional Amount	2,950,000	2,950,000
Derivative, Average Fixed Interest Rate	0.626%	0.626%
Derivative, Average Variable Interest Rate	0.238%	0.246%
Derivative, Weighted Average Remaining Maturity	2.167	2.417
Derivative Maturity Over Three And Within Four Years From Balance Sheet Date [Member]
Derivative [Line Items]
Derivative, Notional Amount	6,300,000	5,300,000
Derivative, Average Fixed Interest Rate	0.936%	0.92%
Derivative, Average Variable Interest Rate	0.236%	0.217%
Derivative, Weighted Average Remaining Maturity	3.199	3.49
Derivative Maturity Over Four Years From Balance Sheet Date [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 1,375,000	$ 1,275,000
Derivative, Average Fixed Interest Rate	1.424%	1.406%
Derivative, Average Variable Interest Rate	0.235%	0.242%
Derivative, Weighted Average Remaining Maturity	4.799	5.041