Segment Reporting (Schedule of Information of Total Assets on Segment Basis) (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Total assets	$ 4,951,900,000
Global Wealth Management [Member]
Total assets	3,637,069,000	2,965,168,000.0
Institutional Group [Member]
Total assets	1,028,948,000	883,235,000.0
Other [Member]
Total assets	$ 285,883,000	$ 364,712,000.0