Common Stock (Antidilutive Shares) (Details) - shares		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock
Common Stock [Line Items]
Antidilutive Securities Excluded from Computation of Diluted Earnings Per Share, Amount		67,739	53,703	56,375
Performance Shares
Common Stock [Line Items]
Performance Shares Payout Level		100.00%	100.00%	100.00%
Antidilutive Securities Excluded from Computation of Diluted Earnings Per Share, Amount	[1]	0	47,246	66,804
Performance shares payout based upon performance		0	0	0

[1] Certain performance shares were excluded from the computation of diluted earnings per share as no payouts would have been required based upon performance at the end of each corresponding period.