Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Schedule of Interest Rate Swap Receivers (Details)

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Derivative Instruments and Hedging Activities Schedule of Interest Rate Swap Receivers (Details) - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Mar. 31, 2017
Dec. 31, 2016
Derivative [Line Items]        
Notional $ 18,429,288,000 $ 31,226,878,000 $ 15,935,535,000 $ 18,802,500,000
Interest Rate Swap [Member] | Short [Member]        
Derivative [Line Items]        
Notional $ 6,176,000,000 $ 5,561,990,000    
Weighted Average Variable Interest Rate 2.292% 1.462%    
Weighted Average Fixed Interest Rate 1.921% 2.211%    
Weighted Average Remaining Maturity 6 years 2 months 30 days 7 years 7 months 28 days    
Interest Rate Swap [Member] | Derivative Maturity Over Two And Within Three Years From Balance Sheet Date [Member] | Short [Member]        
Derivative [Line Items]        
Notional $ 450,000,000 $ 200,000,000    
Weighted Average Variable Interest Rate 1.984% 1.391%    
Weighted Average Fixed Interest Rate 1.763% 1.642%    
Weighted Average Remaining Maturity 2 years 18 days 2 years 7 months 5 days    
Interest Rate Swap [Member] | Derivative Maturity Over Three And Within Four Years From Balance Sheet Date [Member] | Short [Member]        
Derivative [Line Items]        
Notional $ 1,415,000,000 $ 500,000,000    
Weighted Average Variable Interest Rate 2.096% 1.357%    
Weighted Average Fixed Interest Rate 1.774% 1.327%    
Weighted Average Remaining Maturity 2 years 10 months 1 day 3 years 19 days    
Interest Rate Swap [Member] | Derivative Maturity Over Four Years From Balance Sheet Date [Member] | Short [Member]        
Derivative [Line Items]        
Notional $ 4,311,000,000 $ 4,861,990,000    
Weighted Average Variable Interest Rate 2.389% 1.475%    
Weighted Average Fixed Interest Rate 1.985% 2.325%    
Weighted Average Remaining Maturity 7 years 9 months 21 days 8 years 4 months 4 days