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Quarterly Financial Information (Details) $ / shares in Units, $ in Thousands | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Feb. 14, 2017 | Dec. 31, 2016 USD ($) $ / shares | Sep. 30, 2016 USD ($) $ / shares | Jun. 30, 2016 USD ($) $ / shares | Mar. 31, 2016 USD ($) $ / shares | Dec. 31, 2015 USD ($) $ / shares | Sep. 30, 2015 USD ($) $ / shares | Jun. 30, 2015 USD ($) $ / shares | Mar. 31, 2015 USD ($) $ / shares | Dec. 31, 2016 USD ($) $ / shares | Dec. 31, 2015 USD ($) $ / shares | Dec. 31, 2014 USD ($) $ / shares
Net premiums earned |  | $ 552,753 |  | $ 542,429 |  | $ 531,932 |  | $ 522,458 |  | $ 516,087 |  | $ 507,390 |  | $ 490,309 |  | $ 476,123 |  | $ 2,149,572 | $ 1,989,909 | $ 1,852,609
Net investment income earned |  | 35,428 |  | 33,375 |  | 31,182 |  | 30,769 |  | 30,108 |  | 32,061 |  | 32,230 |  | 26,917 |  | 130,754 | 121,316 | 138,708
Net realized (losses) gains |  | (7,686) |  | 3,688 |  | 1,765 |  | (2,704) |  | (2,600) |  | 308 |  | (3,420) |  | 18,883 |  | 3,562 | 31,537 | 37,703
Underwriting income |  | 35,168 |  | 32,033 |  | 43,777 |  | 40,955 |  | 49,053 |  | 44,831 |  | 29,124 |  | 26,021 |  |  |  |
Net income |  | 39,360 |  | 38,502 |  | 43,601 |  | 37,032 |  | 45,389 |  | 46,996 |  | 33,768 |  | 39,708 |  | 158,495 | 165,861 | 141,827
Other comprehensive income (loss) |  | (78,159) |  | (9,798) |  | 36,010 |  | 45,422 |  | (3,386) |  | 6,290 |  | (35,944) |  | 3,827 |  | (6,525) | (29,213) | (5,063)
Comprehensive income (loss) |  | $ (38,799) |  | $ 28,704 |  | $ 79,611 |  | $ 82,454 |  | $ 42,003 |  | $ 53,286 |  | $ (2,176) |  | $ 43,535 |  | $ 151,970 | $ 136,648 | $ 136,764
Basic net income per share | $ / shares |  | $ 0.68 |  | $ 0.66 |  | $ 0.75 |  | $ 0.64 |  | $ 0.79 |  | $ 0.82 |  | $ 0.59 |  | $ 0.70 |  | $ 2.74 | $ 2.90 | $ 2.52
Diluted net income per share | $ / shares |  | 0.67 |  | 0.66 |  | 0.74 |  | 0.63 |  | 0.78 |  | 0.81 |  | 0.58 |  | 0.69 |  | 2.70 | 2.85 | 2.47
Dividends to stockholders | $ / shares |  | $ 0.16 | [1] | $ 0.15 | [1] | $ 0.15 | [1] | $ 0.15 | [1] | $ 0.15 | [1] | $ 0.14 | [1] | $ 0.14 | [1] | $ 0.14 | [1] | $ 0.61 | $ 0.57 | $ 0.53
Price range common stock, high | 44.35 | 44.00 | [2] | 41.30 | [2] | 38.67 | [2] | 36.92 | [2] | 37.91 | [2] | 32.50 | [2] | 29.60 | [2] | 30.10 | [2] |  |  |
Price range of common stock, low | 38.50 | 34.95 | [2] | 35.90 | [2] | 33.60 | [2] | 29.27 | [2] | 30.36 | [2] | 28.10 | [2] | 26.28 | [2] | 25.49 | [2] |  |  |
Accumulated other comprehensive income (loss) [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Other comprehensive income (loss) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (6,525) | $ (29,213) | $ (5,063)
[1] | 1 See Note 19. “Statutory Financial Information, Capital Requirements, and Restrictions on Dividends and Transfers of Funds” for a discussion of dividend restrictions.
[2] | 2 These ranges of high and low prices of the Parent’s common stock, as reported by the NASDAQ Global Select Market, represent actual transactions. Price quotations do not include retail markups, markdowns, and commissions. The range of high and low prices for common stock for the period beginning January 3, 2017 and ending February 14, 2017 was $38.50 to $44.35.

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