Carrying Amount and Estimated Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Carrying Amount
Financial assets
Cash and cash equivalents	$ 406,384	$ 203,790
Debt securities, held-to-maturity	234,992	297,915
Loans receivable, net of ALLL	9,415,553	8,156,310
Total financial assets	10,056,929	8,658,015
Financial liabilities
Term deposits	1,090,394	1,070,208
FHLB advances	8,707	440,175
Repurchase agreements and other borrowed funds	573,560	410,859
Subordinated debentures	139,913	134,051
Total financial liabilities	1,812,574	2,055,293
Estimated Fair Value | Level 1
Financial assets
Cash and cash equivalents	406,384	203,790
Debt securities, held-to-maturity	0	0
Loans receivable, net of ALLL	0	0
Total financial assets	406,384	203,790
Financial liabilities
Term deposits	0	0
FHLB advances	0	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Total financial liabilities	0	0
Estimated Fair Value | Level 2
Financial assets
Cash and cash equivalents	0	0
Debt securities, held-to-maturity	245,559	288,256
Loans receivable, net of ALLL	0	0
Total financial assets	245,559	288,256
Financial liabilities
Term deposits	1,095,288	1,069,777
FHLB advances	8,901	439,615
Repurchase agreements and other borrowed funds	573,560	410,859
Subordinated debentures	122,420	120,302
Total financial liabilities	1,800,169	2,040,553
Estimated Fair Value | Level 3
Financial assets
Cash and cash equivalents	0	0
Debt securities, held-to-maturity	0	0
Loans receivable, net of ALLL	9,400,131	8,079,112
Total financial assets	9,400,131	8,079,112
Financial liabilities
Term deposits	0	0
FHLB advances	0	0
Repurchase agreements and other borrowed funds	0	0
Subordinated debentures	0	0
Total financial liabilities	$ 0	$ 0