Nine Months Ended Sept. 30, 2017 | Year Ended Dec. 31 | ||||||||||||||||||||||
| 2016 | 2015 | 2014 | 2013 | 2012 | |||||||||||||||||||
| Earnings, as defined: | |||||||||||||||||||||||
| Pretax income from operations | $ | 91,441 | $ | 112,037 | $ | 118,874 | $ | 113,045 | $ | 95,877 | $ | 79,509 | |||||||||||
| Add: Fixed charges | 26,269 | 34,849 | 33,073 | 29,686 | 28,325 | 25,215 | |||||||||||||||||
| Total earnings, as defined | $ | 117,710 | $ | 146,886 | $ | 151,947 | $ | 142,731 | $ | 124,202 | $ | 104,724 | |||||||||||
| Fixed charges, as defined: | |||||||||||||||||||||||
| Interest charges | $ | 25,985 | $ | 34,452 | $ | 32,731 | $ | 29,273 | $ | 27,797 | $ | 24,799 | |||||||||||
| Interest component of leases | 284 | 397 | 342 | 413 | 528 | 416 | |||||||||||||||||
| Total fixed charges, as defined | $ | 26,269 | $ | 34,849 | $ | 33,073 | $ | 29,686 | $ | 28,325 | $ | 25,215 | |||||||||||
| Ratio of earnings to fixed charges | 4.5 | 4.2 | 4.6 | 4.8 | 4.4 | 4.2 | |||||||||||||||||
