CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 100,864	$ 53,209	$ 48,250
Investments available-for-sale:
Net change in unrealized gains on investments available-for-sale	(9,925)	(294)	(6,246)
Related income tax expense	2,600	108	2,484
Net investment gains reclassified into earnings	(190)	(1,273)	(1,932)
Related income tax expense	50	504	770
Net effect on other comprehensive income (loss) for the period	(7,465)	(955)	(4,924)
Defined benefit pension plan:
Recognition of unrealized gain (loss)	135	1,202	(651)
Related income tax (expense) benefit	(90)	(490)	258
Net effect on other comprehensive income for the period	45	712	(393)
Total other comprehensive income	(7,420)	(243)	(5,317)
Comprehensive income	$ 93,444	$ 52,966	$ 42,933

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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