Six Months Ended June 30, 2017 | Year Ended Dec. 31 | ||||||||||||||||||||||
| 2016 | 2015 | 2014 | 2013 | 2012 | |||||||||||||||||||
| Earnings, as defined: | |||||||||||||||||||||||
| Pretax income from operations | $ | 94,858 | $ | 234,271 | $ | 202,288 | $ | 205,054 | $ | 148,938 | $ | 168,598 | |||||||||||
| Add: Fixed charges | 56,425 | 112,793 | 109,073 | 105,946 | 104,534 | 103,760 | |||||||||||||||||
| Total earnings, as defined | $ | 151,283 | $ | 347,064 | $ | 311,361 | $ | 311,000 | $ | 253,472 | $ | 272,358 | |||||||||||
| Fixed charges, as defined: | |||||||||||||||||||||||
| Interest charges | $ | 44,684 | $ | 88,671 | $ | 84,040 | $ | 80,218 | $ | 77,866 | $ | 69,074 | |||||||||||
| Interest component of leases | 11,741 | 24,122 | 25,033 | 25,728 | 26,668 | 34,686 | |||||||||||||||||
| Total fixed charges, as defined | $ | 56,425 | $ | 112,793 | $ | 109,073 | $ | 105,946 | $ | 104,534 | $ | 103,760 | |||||||||||
| Ratio of earnings to fixed charges | 2.7 | 3.1 | 2.9 | 2.9 | 2.4 | 2.6 | |||||||||||||||||
