Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net income	$ 184,425	$ 140,273	$ 358,025	$ 273,814
Investments:
Total unrealized investment gains (losses)	(425,805)	396,929	(1,041,487)	611,995
Less applicable tax (expense) benefit	89,423	(138,931)	218,712	(214,254)
Unrealized investment gains (losses), net of tax	(336,382)	257,998	(822,775)	397,741
Deferred acquisition costs:
Unrealized gains (losses) attributable to deferred acquisition costs	2,041	(727)	2,491	(1,497)
Less applicable tax (expense) benefit	(429)	254	(523)	524
Unrealized gains (losses) attributable to deferred acquisition costs, net of tax	1,612	(473)	1,968	(973)
Foreign exchange translation:
Foreign exchange translation adjustments, other than securities	(6,217)	3,302	(7,516)	7,516
Less applicable tax (expense) benefit	1,303	(1,153)	1,579	(1,581)
Foreign exchange translation adjustments, other than securities, net of tax	(4,914)	2,149	(5,937)	5,935
Pension:
Amortization of pension costs	3,778	3,109	7,556	6,218
Experience gain (loss)	0	0	0	371
Pension adjustments	3,778	3,109	7,556	6,589
Less applicable tax (expense) benefit	(794)	(1,088)	(1,587)	(2,306)
Pension adjustments, net of tax	2,984	2,021	5,969	4,283
Other comprehensive income (loss)	(336,700)	261,695	(820,775)	406,986
Comprehensive income (loss)	(152,275)	401,968	(462,750)	680,800
Securities [Member]
Investments:
Unrealized holding gains (losses) arising during period	(417,616)	394,004	(1,029,164)	609,531
Reclassification adjustment for (gains) losses on securities included in net income	(9,431)	681	(10,817)	(354)
Reclassification adjustment for amortization of (discount) and premium	870	(61)	1,560	(498)
Foreign exchange adjustment on securities recorded at fair value	(679)	230	(1,264)	245
Unrealized gains (losses) on securities	(426,856)	394,854	(1,039,685)	608,924
Other Investments [Member]
Investments:
Unrealized gains (losses) on other investments	$ 1,051	$ 2,075	$ (1,802)	$ 3,071

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