Business Changes and Developments Goodwill Associated With Acquisitions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Goodwill [Roll Forward]
Goodwill	$ 218,232	$ 189,274
Goodwill, Acquired During Period	5,476	33,039
Impairment of Goodwill	(28,500)	0	$ 0
Goodwill, Other Changes	(27,274)
Goodwill, Translation Adjustments	(1,473)	(4,081)
Goodwill	166,461	218,232	189,274
Business Combination, Goodwill [Abstract]
Goodwill				$ 194,961
Goodwill, Impaired, Accumulated Impairment Loss				(28,500)
Goodwill	218,232	189,274	189,274	166,461
Investment Banking [Member]
Goodwill [Roll Forward]
Goodwill	114,007	87,028
Goodwill, Acquired During Period	5,476	33,039
Impairment of Goodwill	0
Goodwill, Other Changes	0
Goodwill, Translation Adjustments	(4,207)	(6,060)
Goodwill	115,276	114,007	87,028
Business Combination, Goodwill [Abstract]
Goodwill				115,276
Goodwill, Impaired, Accumulated Impairment Loss				0
Goodwill	114,007	87,028	87,028	115,276
Investment Management [Member]
Goodwill [Roll Forward]
Goodwill	104,225	102,246
Goodwill, Acquired During Period	0	0
Impairment of Goodwill	(28,500)
Goodwill, Other Changes	(27,274)
Goodwill, Translation Adjustments	2,734	1,979
Goodwill	51,185	104,225	102,246
Business Combination, Goodwill [Abstract]
Goodwill				79,685
Goodwill, Impaired, Accumulated Impairment Loss				(28,500)
Goodwill	$ 104,225	$ 102,246	$ 102,246	$ 51,185