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Equity - Common Stock Offering Narrative (Details) - USD ($)
 12 Months Ended
Nov. 28, 2016
Jul. 21, 2016
May 16, 2016
Apr. 01, 2015
Jan. 20, 2015
Jan. 28, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Class of Stock [Line Items]                  
Proceeds from issuance of common stock, net             $ 1,449,581,000 $ 380,620,000 $ 195,869,000
At-the-Market                  
Class of Stock [Line Items]                  
Proceeds from sale of common stock, net of underwriters' discount (in shares)             165,000 0 76,000
Proceeds from issuance of common stock, net             $ 20,100,000    
Maximum shares authorized, value             $ 125,000,000.0    
At-the-Market | Minimum                  
Class of Stock [Line Items]                  
Share price             $ 33.54   $ 21.92
At-the-Market | Maximum                  
Class of Stock [Line Items]                  
Share price             $ 33.95   $ 22.07
Common Stock                  
Class of Stock [Line Items]                  
Proceeds from sale of common stock, net of underwriters' discount (in shares) 17,533,099 19,195,373 10,117,223 8,626,311 12,650,000 9,487,500 47,010,695 12,650,000 9,563,500
Share price         $ 31.75 $ 21.50      
Proceeds from issuance of common stock, net         $ 385,600,000 $ 195,800,000      
Common Stock | Public Offering                  
Class of Stock [Line Items]                  
Proceeds from sale of common stock, net of underwriters' discount (in shares)         11,000,000 8,250,000      
Common Stock | Over-Allotment Option                  
Class of Stock [Line Items]                  
Proceeds from sale of common stock, net of underwriters' discount (in shares)         1,650,000 1,237,500