Financial Information (ASU 2016-15) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from BOLI		$ (7,630)	$ (5,690)
Accounting Standards Update 2016-15
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Proceeds from BOLI	$ 4,997		$ 5,690	$ 11,440	$ 2,740	$ 2,425