Consolidated Statements of Stockholders' Equity - USD ($)
$ in Thousands
Total
Preferred Stock
Common Stock
Capital in Excess of Par Value
Accumulated Deficit
AOCL
Beginning balance, value at Dec. 31, 2017 $ 3,319,609 $ 166,193 $ 4,489 $ 5,193,631 $ (2,044,704) $ 0
Preferred shares outstanding, beginning balance at Dec. 31, 2017   6,900,000        
Common shares outstanding, beginning balance at Dec. 31, 2017     89,774,135      
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Net income 30,718       30,718  
Dividends declared on preferred stock (2,588)       (2,588)  
Net income attributable to common stockholders/after preferred distributions 28,130       28,130  
Dividends declared on common stock (78,581)       (78,581)  
Tax withholdings related to net stock settlements (484)       (484)  
Tax withholdings related to net stock settlements (in shares)     (12,188)      
Repurchase of common shares (104,042)   $ (132)   (103,910)  
Repurchase of common shares (in shares)     (2,632,210)      
Stock-based compensation, net 4,091   $ 9 4,357 (275)  
Stock-based compensation, net (in shares)     183,081      
Ending balance, value at Mar. 31, 2018 3,168,723 $ 166,193 $ 4,366 5,197,988 (2,199,824) 0
Preferred shares outstanding, ending balance at Mar. 31, 2018   6,900,000        
Common shares outstanding, ending balance at Mar. 31, 2018     87,312,818      
Beginning balance, value at Dec. 31, 2017 3,319,609 $ 166,193 $ 4,489 5,193,631 (2,044,704) 0
Preferred shares outstanding, beginning balance at Dec. 31, 2017   6,900,000        
Common shares outstanding, beginning balance at Dec. 31, 2017     89,774,135      
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Net income 77,938          
Net income attributable to common stockholders/after preferred distributions 70,174          
Ending balance, value at Sep. 30, 2018 2,805,358 $ 166,177 $ 4,285 4,989,804 (2,354,908)  
Preferred shares outstanding, ending balance at Sep. 30, 2018   6,900,000        
Common shares outstanding, ending balance at Sep. 30, 2018     85,696,261      
Beginning balance, value at Mar. 31, 2018 3,168,723 $ 166,193 $ 4,366 5,197,988 (2,199,824) 0
Preferred shares outstanding, beginning balance at Mar. 31, 2018   6,900,000        
Common shares outstanding, beginning balance at Mar. 31, 2018     87,312,818      
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Net income 17,164       17,164  
Dividends declared on preferred stock (2,588)       (2,588)  
Net income attributable to common stockholders/after preferred distributions 14,576       14,576  
Dividends declared on common stock (77,143)       (77,143)  
Tax withholdings related to net stock settlements (1,173)   $ (2)   (1,171)  
Tax withholdings related to net stock settlements (in shares)     (28,375)      
Repurchase of common shares (64,123)   $ (80)   (64,043)  
Repurchase of common shares (in shares)     (1,612,236)      
SMTA dividend distribution (216,005)     (216,005)    
Stock-based compensation, net 4,431   $ 2 4,736 (307)  
Stock-based compensation, net (in shares)     42,306      
Ending balance, value at Jun. 30, 2018 2,829,286 $ 166,193 $ 4,286 4,986,719 (2,327,912)  
Preferred shares outstanding, ending balance at Jun. 30, 2018   6,900,000        
Common shares outstanding, ending balance at Jun. 30, 2018     85,714,513      
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Net income 30,056       30,056  
Dividends declared on preferred stock (2,588)       (2,588)  
Net income attributable to common stockholders/after preferred distributions 27,468       27,468  
Dividends declared on common stock (53,546)       (53,546)  
Tax withholdings related to net stock settlements (690)   $ (1)   (689)  
Tax withholdings related to net stock settlements (in shares)     (16,509)      
Issuance of shares, net (16) $ (16)        
Stock-based compensation, net 2,856     3,085 (229)  
Stock-based compensation, net (in shares)     (1,743)      
Ending balance, value at Sep. 30, 2018 2,805,358 $ 166,177 $ 4,285 4,989,804 (2,354,908)  
Preferred shares outstanding, ending balance at Sep. 30, 2018   6,900,000        
Common shares outstanding, ending balance at Sep. 30, 2018     85,696,261      
Beginning balance, value at Dec. 31, 2018 $ 2,801,749 $ 166,177 $ 4,289 4,995,697 (2,357,255) (7,159)
Preferred shares outstanding, beginning balance at Dec. 31, 2018 6,900,000 6,900,000        
Common shares outstanding, beginning balance at Dec. 31, 2018     85,787,355      
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Net income $ 43,578       43,578  
Dividends declared on preferred stock (2,588)       (2,588)  
Net income attributable to common stockholders/after preferred distributions 40,990       40,990  
Other comprehensive Income (loss) (5,021)         (5,021)
Dividends declared on common stock (54,254)       (54,254)  
Tax withholdings related to net stock settlements (704)   $ (1)   (703)  
Tax withholdings related to net stock settlements (in shares)     (17,800)      
Issuance of shares, net 32,686   $ 45 32,641    
Issuance of shares, net (in shares)     893,526      
Other (79)     (79)    
Stock-based compensation, net 3,269   $ 8 3,570 (309)  
Stock-based compensation, net (in shares)     148,705      
Ending balance, value at Mar. 31, 2019 2,818,636 $ 166,177 $ 4,341 5,031,829 (2,371,531) (12,180)
Preferred shares outstanding, ending balance at Mar. 31, 2019   6,900,000        
Common shares outstanding, ending balance at Mar. 31, 2019     86,811,786      
Beginning balance, value at Dec. 31, 2018 $ 2,801,749 $ 166,177 $ 4,289 4,995,697 (2,357,255) (7,159)
Preferred shares outstanding, beginning balance at Dec. 31, 2018 6,900,000 6,900,000        
Common shares outstanding, beginning balance at Dec. 31, 2018     85,787,355      
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Net income $ 170,609          
Net income attributable to common stockholders/after preferred distributions 162,846          
Net reclassification of amounts from AOCL $ (5,003)          
Tax withholdings related to net stock settlements (in shares) (58,000)          
Ending balance, value at Sep. 30, 2019 $ 3,332,780 $ 166,177 $ 4,987 5,544,170 (2,370,392) (12,162)
Preferred shares outstanding, ending balance at Sep. 30, 2019 6,900,000 6,900,000        
Common shares outstanding, ending balance at Sep. 30, 2019     99,730,073      
Beginning balance, value at Mar. 31, 2019 $ 2,818,636 $ 166,177 $ 4,341 5,031,829 (2,371,531) (12,180)
Preferred shares outstanding, beginning balance at Mar. 31, 2019   6,900,000        
Common shares outstanding, beginning balance at Mar. 31, 2019     86,811,786      
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Net income 45,737       45,737  
Dividends declared on preferred stock (2,588)       (2,588)  
Net income attributable to common stockholders/after preferred distributions 43,149       43,149  
Other comprehensive Income (loss) (8,754)         (8,754)
Dividends declared on common stock (56,318)       (56,318)  
Tax withholdings related to net stock settlements (678)   $ (1)   (677)  
Tax withholdings related to net stock settlements (in shares)     (16,367)      
Issuance of shares, net 129,850   $ 165 129,685    
Issuance of shares, net (in shares)     3,292,102      
Stock-based compensation, net 3,575   $ 1 3,882 (308)  
Stock-based compensation, net (in shares)     23,206      
Ending balance, value at Jun. 30, 2019 2,929,460 $ 166,177 $ 4,506 5,165,396 (2,385,685) (20,934)
Preferred shares outstanding, ending balance at Jun. 30, 2019   6,900,000        
Common shares outstanding, ending balance at Jun. 30, 2019     90,110,727      
Increase (Decrease) in Stockholders' Equity [Roll Forward]            
Net income 81,294       81,294  
Dividends declared on preferred stock (2,587)       (2,587)  
Net income attributable to common stockholders/after preferred distributions 78,707       78,707  
Net reclassification of amounts from AOCL 8,772         8,772
Dividends declared on common stock (62,322)       (62,322)  
Tax withholdings related to net stock settlements (1,158)   $ (1)   (1,157)  
Tax withholdings related to net stock settlements (in shares)     (24,229)      
Issuance of shares, net 375,722   $ 482 375,240    
Issuance of shares, net (in shares)     9,646,430      
Stock-based compensation, net 3,599     3,534 65  
Stock-based compensation, net (in shares)     (2,855)      
Ending balance, value at Sep. 30, 2019 $ 3,332,780 $ 166,177 $ 4,987 $ 5,544,170 $ (2,370,392) $ (12,162)
Preferred shares outstanding, ending balance at Sep. 30, 2019 6,900,000 6,900,000        
Common shares outstanding, ending balance at Sep. 30, 2019     99,730,073