UNAUDITED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total		Excluding Life Funds Withheld Assets	Life Funds Withheld Assets	Common Shares	Additional Paid in Capital	AOCI Attributable to Parent [Member]	AOCI Attributable to Parent [Member] Excluding Life Funds Withheld Assets	AOCI Attributable to Parent [Member] Life Funds Withheld Assets	Retained Earnings (Deficit)	Non-controlling Interest in Equity of Consolidated Subsidiaries
Balance, beginning of year at Dec. 31, 2016					$ 2,669	$ 8,068,503	$ 715,546			$ 2,151,794	$ 2,022,167
Issuance of common shares					11
Buybacks of common shares					(111)	(333,747)				(116,772)
Exercise of stock options					17
Exercise of stock options						42,614
Share-based compensation						13,543				(6,089)
Change in net unrealized gains (losses) on investments AFS, net of tax			$ 178,477	$ (32,064)				$ 178,477	$ (32,064)
Change in adjustments related to future policy benefit reserves, net of tax	$ 8,569						8,569
Change in net unrealized gains (losses) on affiliate investments, net of tax	(1,457)						(1,457)
Change in net unrealized gains (losses) on other investments, net of tax	9,338						9,338
Change in OTTI losses recognized in other comprehensive income, net of tax	2,939						2,939
Change in underfunded pension liability, net of tax	(933)						(933)
Change in value of cash flow hedge	(96)						(96)
Foreign currency translation adjustments, net of tax	40,846						40,846
Net income (loss) attributable to common shareholders	454,463									454,463
Dividends on common shares										(117,508)
Non-controlling interests - contributions											25
Non-controlling interests - distributions											(6,093)
Non-controlling interests											5,459
Non-controlling interest share in change in accumulated other comprehensive income (loss)											297
Balance, end of year at Jun. 30, 2017	13,102,407				2,586	7,790,913	921,165			2,365,888	2,021,855
Balance, beginning of year at Dec. 31, 2017	11,461,320				2,560	7,757,940	889,431			1,198,386	1,613,003
Issuance of common shares					7
Buybacks of common shares					0	(1,405)				(651)
Exercise of stock options					21
Exercise of stock options						62,507
Share-based compensation						22,262				(7,075)
Reclassification due to adoption of new accounting pronouncement | Accounting Standards Update 2016-01	(221,856)	[1]					(221,856)			221,856
Reclassification due to adoption of new accounting pronouncement | Accounting Standards Update 2018-02	3,903						3,903			(3,903)
Change in net unrealized gains (losses) on investments AFS, net of tax			$ (509,195)	$ (134,785)				$ (509,195)	$ (134,785)
Change in adjustments related to future policy benefit reserves, net of tax	46,478						46,478
Change in net unrealized gains (losses) on affiliate investments, net of tax	2,275						2,275
Change in net unrealized gains (losses) on other investments, net of tax	0						0
Change in OTTI losses recognized in other comprehensive income, net of tax	5,612						5,612
Change in underfunded pension liability, net of tax	224						224
Change in value of cash flow hedge	(95)						(95)
Foreign currency translation adjustments, net of tax	(30,728)						(30,728)
Net income (loss) attributable to common shareholders	471,644									471,644
Dividends on common shares										(115,402)
Non-controlling interests - contributions											1,924
Non-controlling interests - distributions											(12,153)
Non-controlling interests											(6,552)
Non-controlling interest share in change in accumulated other comprehensive income (loss)											773
Balance, end of year at Jun. 30, 2018	$ 11,257,006				$ 2,588	$ 7,841,304	$ 51,264			$ 1,764,855	$ 1,596,995

[1] The reclassification out of AOCI due to the adoption of ASU 2016-01 includes $233.8 million of net unrealized gains less $11.9 million of deferred tax on net unrealized gains as discussed in Note 1(b), "Significant Accounting Policies - Recent Accounting Pronouncements."