Common Stock (Schedule of changes in number of common stock) (Details) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Equity [Abstract]
Shares outstanding, beginning of period		22,337,644
Initial public offering			23,000,000
Shares repurchased related to employee stock ownership plan			(240,000)
Treasury shares repurchased through stock repurchase authorization	(446,671)		(446,671)
Issuance of treasury shares for vesting of restricted stock units		22,200
Shares outstanding, end of period	22,313,329	22,359,844	22,313,329