Business Changes and Developments - Goodwill Associated with Acquisitions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Balance at beginning of period	$ 130,758	$ 131,387
Goodwill, Impairment Loss	0	(2,921)	$ 0
Foreign Currency Translation and Other	(1,157)	2,292
Sale of ECB Trust Business	(475)
Balance at end of period	129,126	130,758	131,387
Goodwill, Impaired, Accumulated Impairment Loss	38,528	38,528	35,607
Goodwill, Gross	167,654	169,286	166,994
Investment Banking [Member]
Goodwill [Roll Forward]
Balance at beginning of period	122,756	120,464
Goodwill, Impairment Loss		0
Foreign Currency Translation and Other	(1,157)	2,292
Sale of ECB Trust Business	0
Balance at end of period	121,599	122,756	120,464
Investment Management [Member]
Goodwill [Roll Forward]
Balance at beginning of period	8,002	10,923
Goodwill, Impairment Loss		(2,921)
Foreign Currency Translation and Other	0	0
Sale of ECB Trust Business	(475)
Balance at end of period	$ 7,527	$ 8,002	$ 10,923