Short and Long-term Funding Long-term Funding, Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Line Items]
Long-term Debt	$ 549,465
Long term Funding Weighted Average Coupon Rate	3.83%
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 1,632,723	$ 3,180,967
Weighted Average Coupon Rate	2.34%
Long Term Funding Maturity within One Year [Domain]
Debt Disclosure [Line Items]
Long-term Debt	$ 299,631
Long term Funding Weighted Average Coupon Rate	3.50%
Long Term Funding Maturity One Year to Two Years [Domain]
Debt Disclosure [Line Items]
Long-term Debt	$ 967
Long term Funding Weighted Average Coupon Rate	1.07%
Long Term Funding Maturity Two Years to Three Years [Domain]
Debt Disclosure [Line Items]
Long-term Debt	$ 0
Long term Funding Weighted Average Coupon Rate	0.00%
Long Term Funding Maturity Year Three to Year Four [Domain]
Debt Disclosure [Line Items]
Long-term Debt	$ 0
Long term Funding Weighted Average Coupon Rate	0.00%
Long Term Funding Maturity Year Four to Year Five [Domain]
Debt Disclosure [Line Items]
Long-term Debt	$ 248,867
Long term Funding Weighted Average Coupon Rate	4.25%
Long Term Funding Maturity After Year Five [Domain]
Debt Disclosure [Line Items]
Long-term Debt	$ 0
Long term Funding Weighted Average Coupon Rate	0.00%
Maturity or put date 1 year or less
Debt Disclosure [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 17,723
Weighted Average Coupon Rate	2.25%
After 1 but within 2
Debt Disclosure [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 7,383
Weighted Average Coupon Rate	3.70%
After 2 but within 3
Debt Disclosure [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 2,398
Weighted Average Coupon Rate	5.09%
FHLB Maturity Over Three Years to Four Years [Domain]
Debt Disclosure [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 633
Weighted Average Coupon Rate	0.00%
FHLB Maturity Over Four Years to Five Years [Domain]
Debt Disclosure [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 1,000,215
Weighted Average Coupon Rate	2.34%
FHLB Maturity Over Five Years [Domain]
Debt Disclosure [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	$ 604,371
Weighted Average Coupon Rate	2.32%