Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Employee Benefit Plans - Defined Benefit Plans - Fair Value of Assets (Details) - The Bank - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Mutual funds-fixed income
Defined Benefit Plans
Target asset allocations	40.00%
Mutual funds-equity
Defined Benefit Plans
Target asset allocations	60.00%
Cash Balance Plan
Defined Benefit Plans
Assets at Fair Value	$ 20,156	$ 19,254	$ 16,202
Cash Balance Plan \| Level 1
Defined Benefit Plans
Assets at Fair Value	20,156	19,254
Cash Balance Plan \| Mutual funds-fixed income
Defined Benefit Plans
Assets at Fair Value	8,497	7,510
Cash Balance Plan \| Mutual funds-fixed income \| Level 1
Defined Benefit Plans
Assets at Fair Value	8,497	7,510
Cash Balance Plan \| Mutual funds-equity
Defined Benefit Plans
Assets at Fair Value	11,659	11,744
Cash Balance Plan \| Mutual funds-equity \| Level 1
Defined Benefit Plans
Assets at Fair Value	$ 11,659	$ 11,744