| Six Months Ended June 30, | Year Ended December 31, | ||||||||||||||||||||||||||
| 2017 | 2018 | 2013 | 2014 | 2015 | 2016 | 2017 | |||||||||||||||||||||
| Earnings: | |||||||||||||||||||||||||||
Pre-tax earnings(1) | $ | 439,706 | $ | 393,667 | $ | 830,648 | $ | 772,235 | $ | 766,187 | $ | 784,677 | $ | 755,315 | |||||||||||||
| Fixed charges | 44,715 | 42,682 | 86,659 | 85,497 | 78,860 | 77,515 | 81,807 | ||||||||||||||||||||
| Earnings before fixed charges | $ | 484,421 | $ | 436,349 | $ | 917,307 | $ | 857,732 | $ | 845,047 | $ | 862,192 | $ | 837,122 | |||||||||||||
| Fixed charges: | |||||||||||||||||||||||||||
Interest expense(2) | $ | 43,499 | $ | 41,349 | $ | 83,501 | $ | 82,153 | $ | 75,286 | $ | 74,862 | $ | 79,187 | |||||||||||||
| Amortization of bond issue costs | 534 | 506 | 1,031 | 1,192 | 1,356 | 1,264 | 1,274 | ||||||||||||||||||||
| Estimated interest factor of rental expense | 682 | 827 | 2,127 | 2,152 | 2,218 | 1,389 | 1,346 | ||||||||||||||||||||
| Total fixed charges | $ | 44,715 | $ | 42,682 | $ | 86,659 | $ | 85,497 | $ | 78,860 | $ | 77,515 | $ | 81,807 | |||||||||||||
| Ratio of earnings to fixed charges | 10.2 | 10.8 | 10.2 | 11.1 | 10.7 | 10.0 | 10.6 | ||||||||||||||||||||
| Earnings before fixed charges | $ | 484,421 | $ | 436,349 | $ | 917,307 | $ | 857,732 | $ | 845,047 | $ | 862,192 | $ | 837,122 | |||||||||||||
| Interest credited for deposit products | 29,782 | 30,569 | 61,039 | 62,503 | 65,172 | 68,718 | 70,555 | ||||||||||||||||||||
| Adjusted earnings before fixed charges | $ | 514,203 | $ | 466,918 | $ | 978,346 | $ | 920,235 | $ | 910,219 | $ | 930,910 | $ | 907,677 | |||||||||||||
| Fixed charges | $ | 44,715 | $ | 42,682 | $ | 86,659 | $ | 85,497 | $ | 78,860 | $ | 77,515 | $ | 81,807 | |||||||||||||
| Interest credited for deposit products | 29,782 | 30,569 | 61,039 | 62,503 | 65,172 | 68,718 | 70,555 | ||||||||||||||||||||
| Adjusted fixed charges | $ | 74,497 | $ | 73,251 | $ | 147,698 | $ | 148,000 | $ | 144,032 | $ | 146,233 | $ | 152,362 | |||||||||||||
| Ratio of earnings to fixed charges including interest | |||||||||||||||||||||||||||
| credited on deposit products as a fixed charge | 6.4 | 6.9 | 6.0 | 6.4 | 6.3 | 6.2 | 6.6 | ||||||||||||||||||||
| Rental expense | $ | 2,068 | $ | 2,507 | $ | 6,446 | $ | 6,520 | $ | 6,722 | $ | 4,210 | $ | 4,079 | |||||||||||||
| Estimated interest factor of rental expense (33%) | $ | 682 | $ | 827 | $ | 2,127 | $ | 2,152 | $ | 2,218 | $ | 1,389 | $ | 1,346 | |||||||||||||
