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Condensed Financial Information (Parent Company Only) - Condensed Statements of Income (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Condensed Financial Statements, Captions |  |  |
Salaries and benefits | $ 122,751 | $ 108,684 | $ 101,451
Interest expense | 27,934 | 17,661 | 18,060
Acquisition related expenses | 27,156 | 2,821 | 795
Earnings before income tax benefit | 156,722 | 145,259 | 130,457
Income tax benefit | 50,201 | 49,623 | 43,662
Net income | 106,521 | 95,636 | 86,795
Parent Company |  |  |
Condensed Financial Statements, Captions |  |  |
Dividends from subsidiaries | 150,000 | 140,000 | 70,000
Other interest income | 100 | 0 | 0
Other income, primarily management fees from subsidiaries | 18,000 | 15,100 | 13,200
Total income | 168,100 | 155,100 | 83,200
Salaries and benefits | 21,800 | 18,800 | 16,300
Interest expense | 4,700 | 4,100 | 3,800
Acquisition related expenses | 25,300 | 1,500 | 800
Other operating expenses, net | 13,000 | 10,400 | 9,900
Total expenses | 64,800 | 34,800 | 30,800
Earnings before income tax benefit | 103,300 | 120,300 | 52,400
Income tax benefit | (14,200) | (7,700) | (7,000)
Income before undistributed earnings of subsidiaries | 117,500 | 128,000 | 59,400
Undistributed earnings of subsidiaries | (11,000) | (32,400) | 27,400
Net income | $ 106,500 | $ 95,600 | $ 86,800

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