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, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Earnings Per Share [Abstract] | |||||||||||
| Net income | $ 121,297 | $ 450,584 | $ 240,190 | $ 118,157 | $ 154,634 | $ 470,378 | $ 226,676 | $ 103,155 | $ 930,228 | $ 954,843 | $ 759,872 |
| Basic weighted-average shares outstanding | 214,929,977 | 223,001,739 | 228,040,825 | ||||||||
| Dilutive effect of share awards | 1,545,099 | 1,417,466 | 1,377,501 | ||||||||
| Diluted weighted-average shares outstanding | 216,475,076 | 224,419,205 | 229,418,326 | ||||||||
| Basic earnings per share (in dollars per share) | $ 0.57 | $ 2.10 | $ 1.11 | $ 0.54 | $ 0.70 | $ 2.12 | $ 1.02 | $ 0.45 | $ 4.33 | $ 4.28 | $ 3.33 |
| Diluted earnings per share (in dollars per share) | $ 0.56 | $ 2.09 | $ 1.11 | $ 0.54 | $ 0.70 | $ 2.11 | $ 1.01 | $ 0.45 | $ 4.30 | $ 4.25 | $ 3.31 |