Loans Receivable and Allowance for Loan Losses (Narrative) (Detail)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) SecurityLoan borrower troubled_debt_restructuring Contract	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) SecurityLoan borrower troubled_debt_restructuring Contract	May 30, 2014 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Principal amount of nonaccrual loans	$ 43,000,000		$ 43,000,000		$ 44,400,000
Loans less than 90 days past due	4,800,000		$ 4,800,000		$ 18,300,000
Number of loans 90 days past due and still accruing | Contract			0		1
Recorded Investment greater than 90 days accruing	0		$ 0		$ 165,000
Impaired loan defined floor limit (greater than)	1,000,000.0		$ 1,000,000.0
Impaired loans number | SecurityLoan			140		148
Impaired loans	45,317,000		$ 45,317,000		$ 50,867,000
Number of troubled debt restructurings | troubled_debt_restructuring			115		122
Number of borrowers | borrower			114		120
Loans and leases receivable, impaired, nonperforming, accrual of interest	21,300,000		$ 21,300,000		$ 26,000,000
Weighted average modified interest rate		3.53%		5.41%
Weighted average prior modification rate		5.41%		5.80%
Interest income	74,805,000	$ 72,188,000	148,779,000	$ 144,419,000
Average balance of impaired loans			45,727,000		51,225,000
Team Capital Bank [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of acquired loans						$ 5,200,000
Decrease in PCI loans			1,000,000
Balance of PCI loans	2,400,000		2,400,000		3,400,000
Interest income	223,000	145,000	503,000	220,000
Impaired Loans Troubled Debt Restructurings [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowances for loan losses		$ 88,000		$ 173,000
With Related Allowance For Loan Losses [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Allowances for loan losses	2,313,000		2,313,000		2,271,000
No Allowance For Loan Losses Required [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired financing receivable with no related allowance					33,376,000
Loans With No Related Allowance [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired financing receivable with no related allowance	$ 28,280,000		28,280,000
Average balance of impaired loans			$ 28,566,000		$ 33,245,000