Business Combinations - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
	Dec. 23, 2013 Location
Prosperity Bank [Member]
Business Acquisition [Line Items]
Number of banking locations	12
Prosperity Banking Company [Member]
Business Acquisition [Line Items]
Shares to receive for each share of Prosperity common stock pursuant to the merger agreement	3.125
Cash to receive for each share of Prosperity common stock pursuant to the merger agreement	$ 41.50
Issuance of common stock, shares	1,168,918
Issuance of common stock, fair value	$ 24.6