Shareholders' Equity Shareholders' Equity (Details) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended					9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Apr. 30, 2014 Prior to Increase Approved by Shareholders [Member]	Apr. 30, 2014 After Increase Approved by Shareholders [Member]	Sep. 30, 2014 At-the-market equity issuance [Member]	Sep. 30, 2014 At-the-market equity issuance [Member] Gross Proceeds [Member]
Stock Issued During Period, Shares, New Issues						14,600,000
Issuance of common shares	$ 255,962	$ 632,531				$ 256,000	$ 258,600
Common Stock, Shares Authorized	600,000,000		400,000,000	400,000,000	600,000,000