Investment Securities Maturities of Available for sale Securities by Type (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Amortized Cost	$ 1,018,774	$ 1,161,633
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Total	994,065	1,149,534
U.S. government and agencies
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Within one year	9,999
After one, but within five years	10,095
After five, but within ten years	9,949
Greater than ten years	0
Amortized Cost	30,043	35,132
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Within one year	9,974
After one, but within five years	9,802
After five, but within ten years	9,338
Greater than ten years	0
Total	$ 29,114	34,299
Debt Securities, Available-for-sale, Maturity, Weighted Average Yield [Abstract]
Within one year	1.48%
After one, but within five years	1.74%
After five, but within ten years	1.70%
Greater than ten years	0.00%
Total	1.64%
Government-sponsored entities
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Within one year	$ 56,222
After one, but within five years	119,301
After five, but within ten years	36,132
Greater than ten years	0
Amortized Cost	211,655	305,101
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Within one year	56,014
After one, but within five years	117,124
After five, but within ten years	34,565
Greater than ten years	0
Total	$ 207,703	302,501
Debt Securities, Available-for-sale, Maturity, Weighted Average Yield [Abstract]
Within one year	1.76%
After one, but within five years	1.94%
After five, but within ten years	2.05%
Greater than ten years	0.00%
Total	1.91%
Municipal bonds
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Within one year	$ 15,981
After one, but within five years	43,351
After five, but within ten years	52,485
Greater than ten years	198,020
Amortized Cost	309,837	299,647
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Within one year	15,957
After one, but within five years	43,327
After five, but within ten years	52,733
Greater than ten years	196,942
Total	$ 308,959	303,058
Debt Securities, Available-for-sale, Maturity, Weighted Average Yield [Abstract]
Within one year	1.86%
After one, but within five years	2.45%
After five, but within ten years	3.16%
Greater than ten years	3.42%
Total	3.16%
Mortgage-backed securities
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Within one year	$ 35
After one, but within five years	69,607
After five, but within ten years	202,899
Greater than ten years	194,698
Amortized Cost	467,239	521,753
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Within one year	35
After one, but within five years	67,370
After five, but within ten years	193,719
Greater than ten years	187,165
Total	$ 448,289	$ 509,676
Debt Securities, Available-for-sale, Maturity, Weighted Average Yield [Abstract]
Within one year	4.56%
After one, but within five years	2.16%
After five, but within ten years	2.14%
Greater than ten years	2.14%
Total	2.14%