CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - UNAUDITED - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 29,383	$ 29,234	$ 87,976	$ 75,298
Investments available-for-sale:
Net change in unrealized gains on investments available-for-sale	912	(5,399)	16,893	(22,318)
Related income tax expense	(239)	1,411	(4,418)	5,839
Net investment gains reclassified into earnings	(15)	(82)	(20)	(145)
Related income tax expense	4	22	5	38
Net effect on other comprehensive income (loss) for the period	662	(4,048)	12,460	(16,586)
Defined benefit pension plan:
Recognition of unrealized gain (loss)	264	250	794	750
Related income tax (expense) benefit	(69)	(66)	(208)	(250)
Net effect on other comprehensive income for the period	195	184	586	500
Total other comprehensive income	857	(3,864)	13,046	(16,086)
Comprehensive income	$ 30,240	$ 25,370	$ 101,022	$ 59,212

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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