Advances (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Federal Home Loan Bank Advances
Total Par Value	$ 35,482,583	$ 65,439,119
Federal Home Loan Bank, Advances, Five Largest Borrowers Amount Outstanding	$ 24,400,000	$ 50,800,000
Number Of Top Advances Borrowers	5	5
Federal Home Loan Bank, Advances, Five Largest Borrowers, Percent of Total	68.90%	77.70%
Federal Home Loan Bank, Advances, Borrowers With Outstanding Loan Balances Greater Than Ten Percent	3	4
Minimum
Federal Home Loan Bank Advances
Interest rate of advances	0.03%	1.15%
Maximum
Federal Home Loan Bank Advances
Federal Home Loan Bank, Advances, Maturity Period, Fixed Rate	30 years
Federal Home Loan Bank, Advances, Maturity Period, Variable Rate	10 years
Interest rate of advances	6.77%	7.40%