Derivatives (Offsetting Derivative Assets and Liabilities Subject to Master Netting Arrangements) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Gross Amounts Recognized, Derivative Assets	$ 72,731	$ 61,529
Gross Amounts Offset in the Statement of Financial Condition, Derivative Assets	(68,040)	(58,660)
Net Amounts Presented in the Statement of Financial Condition, Derivative Assets	4,691	2,869
Gross Amounts Not Offset in the Statement of Financial Condition - Financial Instruments, Derivative Assets	4,691	2,869
Gross Amounts Not offset in the Statement of Financial Condition - Cash Collateral, Derivative Assets	0	0
Net Amounts Presented in the Statement of Financial Condition, Derivative Assets	0	0
Gross Amounts Recognized, Derivative Liabilities	114,867	171,275
Gross Amounts Offset in the Statement of Financial Condition, Derivative Liabilities	(81,870)	(126,434)
Net Amounts Presented in the Statement of Financial Condition, Derivative Liabilities	32,997	44,841
Gross Amounts Not Offset in the Statement of Financial Condition - Financial Instruments, Derivative Liabilities	4,691	2,869
Gross Amounts Not offset in the Statement of Financial Condition - Cash Collateral, Derivative Liabilities	74,520	90,312
Gross Amounts Not Offset in the Statement of Financial Condition - Net Amount, Derivatives Liabilities	$ (46,214)	$ (48,340)