Investments (Summary Of Unrealized Appreciation (Depreciation) Of Available For Sale, Fixed Maturity And Equity Security Investments) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jun. 30, 2018
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 15,506,555
Unrealized Appreciation	442,861
Unrealized Depreciation	(144,892)
OTTI in AOCI	802
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	15,506,555	$ 15,406,572
Unrealized Appreciation	442,861	186,589
Unrealized Depreciation	(144,892)	(367,898)
Market Value	15,804,524	15,225,263
OTTI in AOCI	802	2,545
U.S. Treasury Securities And Obligations Of U.S. Government Agencies And Corporations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,301,006	2,629,454
Unrealized Appreciation	33,777	16,781
Unrealized Depreciation	(2,578)	(15,101)
Market Value	1,332,205	2,631,134
OTTI in AOCI	0
Obligations Of U.S. States And Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	502,025	490,018
Unrealized Appreciation	27,035	12,915
Unrealized Depreciation	(351)	(2,839)
Market Value	528,709	500,094
OTTI in AOCI	0	439
Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,892,619	5,538,582
Unrealized Appreciation	161,213	48,465
Unrealized Depreciation	(33,382)	(141,515)
Market Value	6,020,450	5,445,532
OTTI in AOCI	368	1,688
Asset-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	759,213	545,427
Unrealized Appreciation	2,346	162
Unrealized Depreciation	(1,958)	(5,492)
Market Value	759,601	540,097
OTTI in AOCI	0
Commercial Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	677,210	329,883
Unrealized Appreciation	26,967	2,167
Unrealized Depreciation	(927)	(5,340)
Market Value	703,250	326,710
OTTI in AOCI	0
Agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,294,248	1,832,760
Unrealized Appreciation	28,879	7,325
Unrealized Depreciation	(11,711)	(43,821)
Market Value	2,311,416	1,796,264
OTTI in AOCI	0
Non-Agency Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,381	10,198
Unrealized Appreciation	39	37
Unrealized Depreciation	(15)	(26)
Market Value	8,405	10,209
OTTI in AOCI	0
Foreign Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,293,568	1,335,328
Unrealized Appreciation	49,162	34,743
Unrealized Depreciation	(39,548)	(55,906)
Market Value	1,303,182	1,314,165
OTTI in AOCI	0	98
Foreign Corporate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,778,285	2,694,922
Unrealized Appreciation	113,443	63,994
Unrealized Depreciation	(54,422)	(97,858)
Market Value	2,837,306	2,661,058
OTTI in AOCI	$ 434	$ 320

Accumulated other comprehensive loss related to portion of other than temporary impairment (OTTI) due to factors other than credit losses on debt securities categorized as available-for-sale that an entity does not intend to sell and which it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis of the debt security. The amount represented by this item is net of tax, as applicable.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 9A
-URI http://asc.fasb.org/extlink&oid=118954083&loc=SL6284427-111562

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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