Business Changes and Developments Intangible Assets Associated with Acquisitions (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	$ 54,269	$ 55,399
Intangible Assets, accumulated amortization	27,538	20,002
Client Related [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	48,130	49,260
Intangible Assets, accumulated amortization	23,858	17,381
Acquired Mandates [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	1,810	1,810
Intangible Assets, accumulated amortization	1,786	1,324
Non-compete/Non-solicit Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	2,084	2,084
Intangible Assets, accumulated amortization	1,408	987
Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	2,245	2,245
Intangible Assets, accumulated amortization	486	310
Investment Banking [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	4,245	4,245
Intangible Assets, accumulated amortization	3,179	2,360
Investment Banking [Member] | Client Related [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	2,300	2,300
Intangible Assets, accumulated amortization	1,299	969
Investment Banking [Member] | Acquired Mandates [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	1,810	1,810
Intangible Assets, accumulated amortization	1,786	1,324
Investment Banking [Member] | Non-compete/Non-solicit Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	135	135
Intangible Assets, accumulated amortization	94	67
Investment Banking [Member] | Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	0	0
Intangible Assets, accumulated amortization	0	0
Investment Management [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	50,024	51,154
Intangible Assets, accumulated amortization	24,359	17,642
Investment Management [Member] | Client Related [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	45,830	46,960
Intangible Assets, accumulated amortization	22,559	16,412
Investment Management [Member] | Acquired Mandates [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	0	0
Intangible Assets, accumulated amortization	0	0
Investment Management [Member] | Non-compete/Non-solicit Agreements [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	1,949	1,949
Intangible Assets, accumulated amortization	1,314	920
Investment Management [Member] | Other [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	2,245	2,245
Intangible Assets, accumulated amortization	$ 486	$ 310