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Amount after adjustments of available-for-sale debt securities at cost, maturing in the next fiscal year following the latest fiscal year. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings less cumulative-effect adjustments, and fair value hedge accounting adjustments. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Mar. 31, 2017
Amortized Cost
Due within one year	$ 41,602
Due after one year through five years	54,549
Due after five years through ten years	80,531
Due after ten years	65,931
Amortized Cost	1,106,028	$ 674,104	$ 2,946
Fair Value
Due within one year	42,138
Due after one year through five years	55,472
Due after five years through ten years	81,272
Due after ten years	64,758
Fair Value	1,088,779	671,488
Other debt securities
Amortized Cost
Amortized Cost	23,555	17,106
Other debt securities, amortized cost	14,736
Fair Value
Other debt securities, fair value	14,499
Fair Value	23,347	17,290
Government agency mortgage backed securities \| Residential mortgage backed securities:
Amortized Cost
Amortized Cost	493,001	196,121
Fair Value
Fair Value	483,125	193,950
Government agency mortgage backed securities \| Commercial mortgage-backed securities
Amortized Cost
Amortized Cost	27,468	31,015
Fair Value
Fair Value	27,189	31,170
Government agency collateralized mortgage obligations \| Residential mortgage backed securities:
Amortized Cost
Amortized Cost	303,625	180,258
Fair Value
Fair Value	296,005	176,639
Government agency collateralized mortgage obligations \| Commercial mortgage-backed securities
Amortized Cost
Amortized Cost	24,585	5,019
Fair Value
Fair Value	$ 24,321	$ 5,006