Acquisitions (Details 4) (USD $)	3 Months Ended	9 Months Ended	0 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Nov. 30, 2012 Plains Capital	Nov. 30, 2012 Plains Capital Common Stock	Nov. 30, 2012 Plains Capital Non-Cumulative Perpetual Preferred Stock, Series B
Acquisitions
Total purchase price			$ 813,500,000
Shares of stock issued as purchase consideration				27,100,000	114,068
Cash consideration			311,800,000
Pro forma financial information
Net interest income	57,212,000	164,980,000
Other revenues	247,764,000	641,201,000
Net income	$ 33,764,000	$ 72,494,000