Equity Common Stock (Details) - shares	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common Stock, Shares Authorized	170,000,000	170,000,000
Common Stock, Shares, Issued	84,208,538	83,731,769
Common Stock, Capital Shares Reserved for Future Issuance	85,791,462	86,268,231