Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, total	$ 287,302	$ 357,949
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, total	288,450	349,895
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, total	907,433	882,872
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, total	914,615	865,831
Mortgage-backed securities and collateralized mortgage obligations of U.S. Government Sponsored Entities
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, total	287,302
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, total	288,450	297,099
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, total	554,889	567,753
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, total	560,351	554,006
Private mortgage-backed securities and collateralized mortgage obligations
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, total	0
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, total	0	21,673
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, total	64,224	55,569
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, total	65,911	$ 55,728
Collateralized loan obligations
Debt Securities, Held-to-maturity, Maturity, Amortized Cost, Net [Abstract]
Held to maturity, amortized cost, due in less than one year	0
Held to maturity, amortized cost, due after one year through five years	0
Held to maturity, amortized cost, due after five years through ten years	0
Held to maturity, amortized cost, due after ten years	0
Held to maturity, amortized cost, total	0
Debt Securities, Held-to-maturity, Maturity, Fair Value [Abstract]
Held to maturity, fair value, due in less than one year	0
Held to maturity, fair value, due after one year through five years	0
Held to maturity, fair value, due after five years through ten years	0
Held to maturity, fair value, due after ten years	0
Held to maturity, fair value, total	0
Debt Securities, Available-for-sale, Amortized Cost, Fiscal Year Maturity [Abstract]
Available for sale, amortized cost, due in less than one year	8,262
Available for sale, amortized cost, due after one year through five years	120,813
Available for sale, amortized cost, due after five years through ten years	150,800
Available for sale, amortized cost, due after ten years	8,445
Available for sale, amortized cost, total	288,320
Debt Securities, Available-for-sale, Fair Value, Fiscal Year Maturity [Abstract]
Available for sale, fair value, due in less than one year	8,288
Available for sale, fair value, due after one year through five years	120,747
Available for sale, fair value, due after five years through ten years	150,501
Available for sale, fair value, due after ten years	8,817
Available for sale, fair value, total	$ 288,353