Short-Term and Other Borrowings (Details 1) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of other borrowing capacities
Total FHLB borrowing capacity	$ 8,964,608,000	$ 4,569,563,000	$ 3,893,066,000
Unused federal funds lines available from commercial banks	1,432,000,000	620,000,000	885,000,000
Unused Federal Reserve borrowings capacity	3,637,238,000	4,933,965,000	4,114,594,000
Unused revolving line of credit	130,000,000	130,000,000	130,000,000
Average amount oustanding	0	0
FHLB borrowing capacity relating to loans
Summary of other borrowing capacities
Total FHLB borrowing capacity	8,964,019,000	4,568,842,000	3,890,995,000
FHLB borrowing capacity relating to securities
Summary of other borrowing capacities
Total FHLB borrowing capacity	$ 589,000	$ 721,000	$ 2,071,000