Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income	$ 133,541	$ 124,033
Unrealized gains (losses) on securities:
Total unrealized investment gains (losses)	215,066	464,593
Less applicable tax (expense) benefit	(75,323)	(162,589)
Unrealized investment gains (losses), net of tax	139,743	302,004
Unrealized gains (losses) attributable to deferred acquisition costs	(770)	(2,769)
Less applicable tax (expense) benefit	270	969
Unrealized gains (losses) attributable to deferred acquisition costs, net of tax	(500)	(1,800)
Foreign exchange translation adjustments, other than securities	4,214	1,760
Less applicable tax (expense) benefit	(428)	(540)
Foreign exchange translation adjustments, other than securities, net of tax	3,786	1,220
Amortization of pension costs	3,109	2,552
Experience gain (loss)	371	686
Pension adjustments	3,480	3,238
Less applicable tax (expense) benefit	(1,218)	(1,134)
Pension adjustments, net of tax	2,262	2,104
Other comprehensive income (loss)	145,291	303,528
Comprehensive income (loss)	278,832	427,561
Securities [Member]
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during period	215,527	465,157
Reclassification adjustment for (gains) losses on securities included in net income	(1,035)	(313)
Reclassification adjustment for amortization of (discount) and premium	(437)	(1,364)
Foreign exchange adjustment on securities recorded at fair value	15	455
Unrealized gains (losses) on securities	214,070	463,935
Other Investments [Member]
Unrealized gains (losses) on securities:
Unrealized gains (losses) on other investments	$ 996	$ 658