Debt Securities Held to Maturity Expected Maturities of Held-to-Maturity Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Amortized Cost
Amortized cost	$ 299,605	$ 262,143
Fair Value
Fair value	303,179	254,841
U.S. government and agency obligations
Amortized Cost
More than five years to ten years	28,406
More than ten years	10,000
Amortized cost	38,406	23,404
Fair Value
More than five years to ten years	28,443
More than ten years	10,078
Fair value	38,521	23,241
Mortgage-backed securities and collateralized mortgage obligations
Amortized Cost
Amortized cost	261,199	238,739
Fair Value
Fair value	$ 264,658	$ 231,600

Amount of investment in debt security measured at amortized cost (held-to-maturity).

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