Fair Value Measurements (Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		$ 104,344	$ 100,307
Total gains or losses (realized /unrealized), included in earnings		(13,494)	(1,527)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	[1]	(1,495)	364
Discount accretion		4	7
Purchase of private equity securities		114	2,060
Sales And Repayments Of Private Equity Securities		(69)	0
Sale Of Risk Participation Agreement		(440)	0
Ending balance		88,964	101,211
Total gains or losses included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end		(13,063)	(991)
Gains (Losses) included in OCI Attributable to Change in Unrealized Gains (Losses) Relating to Assets Still Held, Total		(1,495)
State and Municipal Obligations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		9,853	14,158
Total gains or losses (realized /unrealized), included in earnings		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	[1]	(1,495)	364
Discount accretion		4	7
Purchase of private equity securities		0	0
Sales And Repayments Of Private Equity Securities		0	0
Sale Of Risk Participation Agreement		0	0
Ending balance		8,362	14,529
Total gains or losses included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end		0	0
Gains (Losses) included in OCI Attributable to Change in Unrealized Gains (Losses) Relating to Assets Still Held, Total		(1,495)
Private Equity Funds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		94,122	85,659
Total gains or losses (realized /unrealized), included in earnings		(13,008)	(1,842)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	[1]	0	0
Discount accretion		0	0
Purchase of private equity securities		114	2,060
Sales And Repayments Of Private Equity Securities		(69)	0
Sale Of Risk Participation Agreement		0	0
Ending balance		81,159	85,877
Total gains or losses included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end		(13,008)	(1,842)
Gains (Losses) included in OCI Attributable to Change in Unrealized Gains (Losses) Relating to Assets Still Held, Total		0
Derivative Level Three Unobservable Inputs [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance		369	490
Total gains or losses (realized /unrealized), included in earnings		(486)	315
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	[1]	0	0
Discount accretion		0	0
Purchase of private equity securities		0	0
Sales And Repayments Of Private Equity Securities		0	0
Sale Of Risk Participation Agreement		(440)	0
Ending balance		(557)	805
Total gains or losses included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end		(55)	$ 851
Gains (Losses) included in OCI Attributable to Change in Unrealized Gains (Losses) Relating to Assets Still Held, Total		$ 0

[1] * Included in "net unrealized gains (losses) on other securities" in the consolidated statements of comprehensive income.