Securities, AFS Debt Securities, Contractual Maturities (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Available-for-sale Securities, Debt Maturities, Amortized Cost [Abstract]
Within one year	$ 44,262
From one to five years	84,391
From five to ten years	163,400
After ten years	725,573
Amortized cost	1,017,626
Available-for-sale Securities, Debt Maturities, Estimated Fair Value [Abstract]
Within one year	44,218
From one to five years	83,441
From five to ten years	160,898
After ten years	709,939
Fair value	$ 998,496

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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