Fair Value Measurements (Summary of Changes in Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	$ 73,271	$ 67,760
Total gains or losses (realized/unrealized) included in earnings	13,954	(5,567)
Total gains losses (realized/unrealized) included in other comprehensive income	(274)	882
Investment securities called	(2,616)	(600)
Discount accretion	32	52
Purchases of private equity securities	16,395	13,352
Sale / paydown of private equity securities	(371)	(2,621)
Capitalized interest/dividends	34	34
Purchase of risk participation agreement	61	70
Sale of risk participation agreement	(179)	(91)
Ending balance	100,307	73,271
Total gains or losses for the annual period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end	14,512	(5,043)
State and Municipal Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	17,016	16,682
Total gains or losses (realized/unrealized) included in earnings	0	0
Total gains losses (realized/unrealized) included in other comprehensive income	(274)	882
Investment securities called	(2,616)	(600)
Discount accretion	32	52
Purchases of private equity securities	0	0
Sale / paydown of private equity securities	0	0
Capitalized interest/dividends	0	0
Purchase of risk participation agreement	0	0
Sale of risk participation agreement	0	0
Ending balance	14,158	17,016
Total gains or losses for the annual period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end	0	0
Private Equity Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	55,752	50,820
Total gains or losses (realized/unrealized) included in earnings	13,849	(5,833)
Total gains losses (realized/unrealized) included in other comprehensive income	0	0
Investment securities called	0	0
Discount accretion	0	0
Purchases of private equity securities	16,395	13,352
Sale / paydown of private equity securities	(371)	(2,621)
Capitalized interest/dividends	34	34
Purchase of risk participation agreement	0	0
Sale of risk participation agreement	0	0
Ending balance	85,659	55,752
Total gains or losses for the annual period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end	13,849	(5,658)
Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	503	258
Total gains or losses (realized/unrealized) included in earnings	105	266
Total gains losses (realized/unrealized) included in other comprehensive income	0	0
Investment securities called	0	0
Discount accretion	0	0
Purchases of private equity securities	0	0
Sale / paydown of private equity securities	0	0
Capitalized interest/dividends	0	0
Purchase of risk participation agreement	61	70
Sale of risk participation agreement	(179)	(91)
Ending balance	490	503
Total gains or losses for the annual period included in earnings attributable to the change in unrealized gains or losses relating to assets still held at period end	$ 663	$ 615