CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 29,234	$ 15,089	$ 75,298	$ 44,942
Investments available-for-sale:
Net change in unrealized gains on investments available-for-sale	(5,399)	113	(22,318)	5,618
Related income tax expense	1,411	(45)	5,839	(2,236)
Net investment gains reclassified into earnings	(82)	0	(145)	(1,275)
Related income tax expense	22	0	38	508
Net effect on other comprehensive income (loss) for the period	(4,048)	68	(16,586)	2,615
Defined benefit pension plan:
Recognition of unrealized gain (loss)	250	296	750	886
Related income tax (expense) benefit	(66)	(129)	(250)	(364)
Net effect on other comprehensive income for the period	184	167	500	522
Total other comprehensive income	(3,864)	235	(16,086)	3,137
Comprehensive income	$ 25,370	$ 15,324	$ 59,212	$ 48,079

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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