FAIR VALUES OF FINANCIAL INSTRUMENTS - Carrying Amounts and Estimated Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financial assets
Cash and cash equivalents	$ 439,510	$ 156,124
Time deposits in financial institutions	1,000	1,500
Securities available-for-sale	2,381,488	833,596
Securities held-to-maturity	899,743	932,285
Federal Home Loan Bank and other bank stock	67,842	59,069
Loans held-for-sale	711,188	672,850
Loans and leases receivable, net of allowance	5,999,791	5,244,251
Accrued interest receivable	36,382	22,800
Derivative assets	17,968	9,042
Financial liabilities
Deposits	8,908,406	6,010,606
Advances from Federal Home Loan Bank	490,351	929,727
Other borrowings	68,000
Long term debt	174,006	264,269
Derivative liabilities	2,116	1,067
Accrued interest payable	4,114	4,234
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial assets
Cash and cash equivalents	439,510	156,124
Time deposits in financial institutions	1,000	1,500
Securities available-for-sale	0	0
Securities held-to-maturity	0	0
Federal Home Loan Bank and other bank stock	0	0
Loans held-for-sale	0	0
Loans and leases receivable, net of allowance	0	0
Accrued interest receivable	36,382	22,800
Derivative assets	0	0
Financial liabilities
Deposits	0	0
Advances from Federal Home Loan Bank	0	0
Other borrowings	0
Long term debt	0	0
Derivative liabilities	0	0
Accrued interest payable	4,114	4,234
Significant Other Observable Inputs (Level 2)
Financial assets
Cash and cash equivalents	0	0
Time deposits in financial institutions	0	0
Securities available-for-sale	2,381,488	833,596
Securities held-to-maturity	899,743	932,285
Federal Home Loan Bank and other bank stock	67,842	59,069
Loans held-for-sale	652,928	654,559
Loans and leases receivable, net of allowance	0	0
Accrued interest receivable	0	0
Derivative assets	17,968	9,042
Financial liabilities
Deposits	0	0
Advances from Federal Home Loan Bank	490,351	929,727
Other borrowings	68,000
Long term debt	174,006	264,269
Derivative liabilities	2,116	1,067
Accrued interest payable	0	0
Significant Unobservable Inputs (Level 3)
Financial assets
Cash and cash equivalents	0	0
Time deposits in financial institutions	0	0
Securities available-for-sale	0	0
Securities held-to-maturity	0	0
Federal Home Loan Bank and other bank stock	0	0
Loans held-for-sale	58,260	18,291
Loans and leases receivable, net of allowance	5,999,791	5,244,251
Accrued interest receivable	0	0
Derivative assets	0	0
Financial liabilities
Deposits	8,908,406	6,010,606
Advances from Federal Home Loan Bank	0	0
Other borrowings	0
Long term debt	0	0
Derivative liabilities	0	0
Accrued interest payable	0	0
Carrying Value
Financial assets
Cash and cash equivalents	439,510	156,124
Time deposits in financial institutions	1,000	1,500
Securities available-for-sale	2,381,488	833,596
Securities held-to-maturity	884,234	962,203
Federal Home Loan Bank and other bank stock	67,842	59,069
Loans held-for-sale	704,651	668,841
Loans and leases receivable, net of allowance	5,994,308	5,148,861
Accrued interest receivable	36,382	22,800
Derivative assets	17,968	9,042
Financial liabilities
Deposits	9,142,150	6,303,085
Advances from Federal Home Loan Bank	490,000	930,000
Other borrowings	67,922
Long term debt	175,378	261,876
Derivative liabilities	2,116	1,067
Accrued interest payable	$ 4,114	$ 4,234