Common Stock Common Stock (Details) - shares	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Sales Agency Agreements Common Stock, Shares Authorized	200,000,000	200,000,000
Document Period End Date	Mar. 31, 2019
Sales Agency Agreement [Member]
Class of Stock [Line Items]
Shares issued from sales agency agreements	0
Sales Agency Agreements Common Stock, Shares Authorized	3,800,000
Common Stock Shares Authorized Under Sales Agency Agreements Remaining Shares Authorized To Sell	1,100,000