Carrying Amount and Estimated Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Carrying Amount
Financial assets
Cash and cash equivalents	$ 202,527	$ 203,790
Debt securities, held-to-maturity	255,572	297,915
Loans receivable, net of ALLL	8,196,284	8,156,310
Total financial assets	8,654,383	8,658,015
Financial liabilities
Term deposits	1,089,684	1,070,208
FHLB advances	154,683	440,175
Repurchase agreements and other borrowed funds	504,358	410,859
Subordinated debentures	134,048	134,051
Total financial liabilities	1,882,773	2,055,293
Estimated Fair Value | Level 1
Financial assets
Cash and cash equivalents	202,527	203,790
Debt securities, held-to-maturity	0	0
Loans receivable, net of ALLL	0	0
Total financial assets	202,527	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	261,408	288,256
Loans receivable, net of ALLL	0	0
Total financial assets	261,408	288,256
Financial liabilities
Term deposits	1,089,785	1,069,777
FHLB advances	154,915	439,615
Repurchase agreements and other borrowed funds	504,358	410,859
Subordinated debentures	121,369	120,302
Total financial liabilities	1,870,427	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	8,148,954	8,079,112
Total financial assets	8,148,954	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