Equity Other Equity Activity (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock		$ 464,023	$ 323,798
At the Market Stock Offering Program, capacity remaining	$ 150,000	150,000
Common Stock, Capital Shares Reserved for Future Issuance	500,000	500,000
At the Market Program [Member]
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock		22,009
Payments of Stock Issuance Costs		200
Common Stock [Member]
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock	$ 47	$ 51
Stock Issued During Period, Shares, New Issues	4,750,000	4,992,300
Common Stock [Member] | At the Market Program [Member]
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock			$ 38
Stock Issued During Period, Shares, New Issues		242,300	3,828,064