Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Reconciliation between Basic and Diluted Earnings Per Share (Details)

v3.8.0.1
Summary of Significant Accounting Policies - Reconciliation between Basic and Diluted Earnings Per Share (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2017
Sep. 30, 2017
Jun. 30, 2017
Mar. 31, 2017
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Earnings Per Share [Abstract]                      
Net income $ 98,797 $ 400,692 $ 198,473 $ 61,910 $ 72,232 $ 342,378 $ 145,246 $ 73,229 $ 759,872 $ 633,085 $ 427,137
Basic weighted-average shares outstanding                 228,040,825 227,121,875 226,591,437
Potentially dilutive shares                 1,377,501 728,411 3,448,695
Diluted weighted-average shares outstanding                 229,418,326 227,850,286 230,040,132
Basic EPS (in dollars per share) $ 0.43 $ 1.76 $ 0.87 $ 0.27 $ 0.32 $ 1.51 $ 0.64 $ 0.32 $ 3.33 $ 2.79 $ 1.89
Diluted EPS (in dollars per share) $ 0.43 $ 1.74 $ 0.87 $ 0.27 $ 0.32 $ 1.50 $ 0.64 $ 0.32 $ 3.31 $ 2.78 $ 1.86