For investments which are quantified by principal amount, the principle balance held at close of period.

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Related Party Transactions - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Unfunded commitments	$ 3		$ 2
Deposits from related parties	107,453		110,465
Aviation Time Sharing Agreement
Related Party Transaction [Line Items]
Payments to related party	72	$ 25
Certain Executive Officers and Directors and Their Associates
Related Party Transaction [Line Items]
Unfunded commitments	6,373		4,672
Shareholders
Related Party Transaction [Line Items]
Unamortized leasehold improvements	132		137
Lease expense	148	$ 126
Director
Related Party Transaction [Line Items]
Amount of investment held by the company	$ 183		$ 200