Other Borrowings - Summary of Other Borrowings (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Total other borrowings	$ 100,293	$ 194,572	$ 0
Fixed Rate Advance One [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Advance from Federal Home Loan Bank with a fixed interest rate of 0.17%, due January 24, 2014	5,000		0
Fixed Rate Advance Two [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Advance from Federal Home Loan Bank with a fixed interest rate of 0.17%, due January 24, 2014	5,000		0
Fixed Rate Advance Three [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Advance from Federal Home Loan Bank with a fixed interest rate of 0.17%, due January 24, 2014	3,000		0
Fixed Rate Advance Four [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Advance from Federal Home Loan Bank with a fixed interest rate of 0.17%, due January 24, 2014		165,000	0
Federal Home Loan Bank Advances [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Daily Rate Credit from Federal Home Loan Bank with a fixed interest rate of 0.36%	40,000		0
Revolving Credit Facility [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Advances under revolving credit agreement with a regional bank with interest at 90-day LIBOR plus 4.00% (4.23% at June 30, 2014) due in August 2016, secured by subsidiary bank stock	22,500	10,000	0
Correspondent Bank Advances [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Advance from correspondent bank with a fixed interest rate of 4.50%, due November 27, 2017, secured by subsidiary bank loan receivable	4,936		0
Subordinated Debt One [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Subordinated debt issued by Prosperity Bank due June 2016 with an interest rate of 90-day LIBOR plus 1.60% (1.84% at June 30, 2014)	5,000	5,000	0
Subordinated Debt Two [Member]
Federal Home Loan Bank Borrowings By Year Of Maturity And Applicable Interest Rate [Line Items]
Subordinated debt issued by Prosperity Bank due June 2016 with an interest rate of 90-day LIBOR plus 1.60% (1.84% at June 30, 2014)	$ 14,857	$ 14,572	$ 0