Leases (Narrative) (Details) - USD ($) $ in Thousands		3 Months Ended			12 Months Ended
		Mar. 31, 2019		Mar. 31, 2018	Dec. 31, 2018	Jan. 01, 2019
Operating lease right-of-use assets		$ 28,249			$ 0	$ 28,923
Operating lease liabilities		$ 30,187	[1]		$ 0	$ 30,853
Operating lease weighted average discount rate		3.66%
Operating leases, weighted average lease term		14 years 4 months 25 days
Operating lease rent expense	[2]	$ 939		$ 916
Options to extend reasonably certain of being exercised		4,700
Short-term operating lease liabilities		$ 2,500
Minimum [Member]
Lease Expiration Period		2 months			5 months
Operating lease renewal term		1 year
Lease Expiration Period, Renewal Option					1 year
Maximum [Member]
Lease Expiration Period		22 years			22 years
Operating lease renewal term		5 years
Lease Expiration Period, Renewal Option					5 years

[1] Includes short-term operating lease liabilities of $2.5 million.

[2] Included in net occupancy expenses in the Unaudited Consolidated Income Statement.