Leases - Narrative (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Lease, Weighted Average Remaining Lease Term	7 years 6 months
Operating Lease, Liability	$ 15,576,000	$ 0
Deferred Rent Credit		600,000
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets			$ (995,000)
Operating Lease, Right-of-Use Asset	$ 14,784,000	0
Operating Lease, Weighted Average Discount Rate, Percent	3.10%
Other Assets [Member]
Operating Lease, Right-of-Use Asset	$ 14,800,000	11,000,000.0
Other Liabilities [Member]
Operating Lease, Liability	$ 15,576,000	11,800,000
Retained Earnings [Member]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		(143,000)
Adjustments for Change in Accounting Principle [Domain] \| Retained Earnings [Member]
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets		$ 143,000

The cumulative difference between the rental payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense over the term of the leased property by the lessor or lessee, respectively.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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Present value of lessee's discounted obligation for lease payments from operating lease.

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Amount of lessee's right to use underlying asset under operating lease.

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Weighted average discount rate for operating lease calculated at point in time.

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Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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