Fair Value Measurements (Detail 4) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Rochdale Investment Management, LLC
Total realized/unrealized gains (losses):
Contingent consideration paid to shareholders			$ 17,400,000
Contingent Consideration Liability
Level 3 Liabilities Measured on a Recurring Basis
Balance, beginning of period	(34,983,000)	(49,900,000)
Total realized/unrealized gains (losses):
Settlements		16,250,000
Other	(418,000)	(411,000)
Balance, end of period	(35,401,000)	(34,061,000)
Contingent Consideration Liability | Rochdale Investment Management, LLC
Total realized/unrealized gains (losses):
Business Acquisition Period of Additional Cash Consideration Payment	6 years
Low-end of the potential range of estimate of total consideration payment	30,000,000
High-end of the potential range of estimate of total consideration payment	53,000,000
FDIC Clawback Liability
Level 3 Liabilities Measured on a Recurring Basis
Balance, beginning of period	(15,106,000)	(11,967,000)
Total realized/unrealized gains (losses):
Included in earnings	(857,000)	(964,000)
Balance, end of period	$ (15,963,000)	$ (12,931,000)