Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended		12 Months Ended
	Jun. 05, 2015	Jul. 31, 2014	Feb. 15, 2013	Dec. 31, 2014	Nov. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Number of shares authorized to be repurchased						5,800,000
Purchase of treasury stock						$ 117,752		$ 13,670
Treasury Stock, Shares, Acquired						2,700,000
Treasury Stock Acquired, Average Cost Per Share						$ 43.91
Shares issued during the period							2,600,000	8,800,000
Common stock reissued								500,000
Sterne Agee Group, Inc. [Member]
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Stock Issued During Period Shares Acquisitions	1,400,000
KBW [Member]
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Stock Issued During Period Shares Acquisitions			6,700,000
Ziegler Lotsoff Capital Management, LLC [Member]
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Stock Issued During Period Shares Acquisitions					100,000
Ouriel Securities [Member]
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Stock Issued During Period Shares Acquisitions		300,000
Merchant Capital LLC [Member]
Business Acquisition Equity Interests Issued Or Issuable [Line Items]
Stock Issued During Period Shares Acquisitions				100,000