Carrying Amount and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Carrying Amount
Financial Assets
Cash and cash equivalents	$ 152,541	$ 193,253
Investment securities, available-for-sale	2,425,477	2,610,760
Investment securities, held-to-maturity	675,674	702,072
Loans held-for-sale	72,927	56,514
Loans receivable, net of ALLL	5,554,891	4,948,984
Accrued interest receivable	45,832	44,524
Non-marketable equity securities	25,550	27,495
Total financial assets	8,952,892	8,583,602
Financial Liabilities
Deposits	7,372,279	6,945,008
FHLB advances	251,749	394,131
Repurchase agreements and other borrowed funds	478,090	430,016
Subordinated debentures	125,991	125,848
Accrued interest payable	3,584	3,517
Interest rate swaps	14,725	19,499
Total financial liabilities	8,246,418	7,918,019
Estimated Fair Value | Level 1
Financial Assets
Cash and cash equivalents	152,541	193,253
Investment securities, available-for-sale	0	0
Investment securities, held-to-maturity	0	0
Loans held-for-sale	72,927	56,514
Loans receivable, net of ALLL	0	0
Accrued interest receivable	45,832	44,524
Non-marketable equity securities	0	0
Total financial assets	271,300	294,291
Financial Liabilities
Deposits	6,090,879	5,654,638
FHLB advances	0	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Accrued interest payable	3,584	3,517
Interest rate swaps	0	0
Total financial liabilities	6,094,463	5,658,155
Estimated Fair Value | Level 2
Financial Assets
Cash and cash equivalents	0	0
Investment securities, available-for-sale	2,425,477	2,610,760
Investment securities, held-to-maturity	689,089	729,513
Loans held-for-sale	0	0
Loans receivable, net of ALLL	5,380,286	4,851,934
Accrued interest receivable	0	0
Non-marketable equity securities	25,550	27,495
Total financial assets	8,520,402	8,219,702
Financial Liabilities
Deposits	1,283,532	1,293,506
FHLB advances	257,643	401,530
Repurchase agreements and other borrowed funds	478,090	430,016
Subordinated debentures	85,557	81,840
Accrued interest payable	0	0
Interest rate swaps	14,725	19,499
Total financial liabilities	2,119,547	2,226,391
Estimated Fair Value | Level 3
Financial Assets
Cash and cash equivalents	0	0
Investment securities, available-for-sale	0	0
Investment securities, held-to-maturity	0	0
Loans held-for-sale	0	0
Loans receivable, net of ALLL	123,382	132,649
Accrued interest receivable	0	0
Non-marketable equity securities	0	0
Total financial assets	123,382	132,649
Financial Liabilities
Deposits	0	0
FHLB advances	0	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Accrued interest payable	0	0
Interest rate swaps	0	0
Total financial liabilities	$ 0	$ 0