Three Months Ended March 31, 2018 | Year Ended Dec. 31 | ||||||||||||||||||||||
| 2017 | 2016 | 2015 | 2014 | 2013 | |||||||||||||||||||
| Earnings, as defined: | |||||||||||||||||||||||
| Pretax income | $ | 172,731 | $ | 746,298 | $ | 737,409 | $ | 745,242 | $ | 698,779 | $ | 704,123 | |||||||||||
| Add: Fixed charges | 61,779 | 241,434 | 236,080 | 235,530 | 232,832 | 232,539 | |||||||||||||||||
| Total earnings, as defined | $ | 234,510 | $ | 987,732 | $ | 973,489 | $ | 980,772 | $ | 931,611 | $ | 936,662 | |||||||||||
| Fixed charges, as defined: | |||||||||||||||||||||||
| Interest charges | $ | 49,921 | $ | 190,694 | $ | 181,631 | $ | 177,430 | $ | 171,881 | $ | 173,602 | |||||||||||
| Interest charges on life insurance policy borrowings | 57 | 271 | 203 | 233 | 214 | 245 | |||||||||||||||||
| Interest component of leases | 11,801 | 50,469 | 54,246 | 57,867 | 60,737 | 58,692 | |||||||||||||||||
| Total fixed charges, as defined | $ | 61,779 | $ | 241,434 | $ | 236,080 | $ | 235,530 | $ | 232,832 | $ | 232,539 | |||||||||||
| Ratio of earnings to fixed charges | 3.8 | 4.1 | 4.1 | 4.2 | 4.0 | 4.0 | |||||||||||||||||
