Business Changes and Developments - Goodwill Associated with Acquisitions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance at beginning of period	$ 134,231	$ 160,961
Impairment of Goodwill		(7,107)
Sale of the Institutional Trust and Independent Fiduciary business of ETC		(28,442)
Foreign Currency Translation and Other	(2,844)	8,819
Balance at end of period	131,387	134,231
Goodwill, Impaired, Accumulated Impairment Loss	35,607	35,607	$ 28,500
Goodwill, Gross	166,994	169,838	$ 189,461
Investment Banking [Member]
Goodwill [Roll Forward]
Balance at beginning of period	123,308	114,489
Impairment of Goodwill		0
Sale of the Institutional Trust and Independent Fiduciary business of ETC		0
Foreign Currency Translation and Other	(2,844)	8,819
Balance at end of period	120,464	123,308
Investment Management [Member]
Goodwill [Roll Forward]
Balance at beginning of period	10,923	46,472
Impairment of Goodwill		(7,107)
Sale of the Institutional Trust and Independent Fiduciary business of ETC		(28,442)
Foreign Currency Translation and Other	0	0
Balance at end of period	$ 10,923	$ 10,923