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Investments (Fair Value and Gross Pre-Tax Net Unrealized Unrecognized Loss of Securities By Length of Time) (Details) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
AFS Fair Value, Less than 12 months		$ 383,502	$ 1,449,183
AFS Unrealized Losses, Less than 12 months	[1]	(5,104)	(19,953)
AFS Fair Value, 12 months or longer		179,396	141,580
AFS Unrealized Losses, 12 months or longer	[1]	(3,012)	(4,900)
AFS Fixed Income Securities [Member]
AFS Fair Value, Less than 12 months		377,562	1,416,504
AFS Unrealized Losses, Less than 12 months	[1]	(4,779)	(17,915)
AFS Fair Value, 12 months or longer		179,396	141,580
AFS Unrealized Losses, 12 months or longer	[1]	(3,012)	(4,900)
AFS Fixed Income Securities [Member] | U.S. Government and Government Agencies [Member]
AFS Fair Value, Less than 12 months		0	16,006
AFS Unrealized Losses, Less than 12 months	[1]	0	(87)
AFS Fair Value, 12 months or longer		400	396
AFS Unrealized Losses, 12 months or longer	[1]	(1)	(4)
AFS Fixed Income Securities [Member] | Foreign Government [Member]
AFS Fair Value, Less than 12 months			1,067
AFS Unrealized Losses, Less than 12 months	[1]		(2)
AFS Fair Value, 12 months or longer			0
AFS Unrealized Losses, 12 months or longer	[1]		0
AFS Fixed Income Securities [Member] | Obligations of States and Political Subdivisions [Member]
AFS Fair Value, Less than 12 months		25,867	28,617
AFS Unrealized Losses, Less than 12 months	[1]	(123)	(160)
AFS Fair Value, 12 months or longer		820	0
AFS Unrealized Losses, 12 months or longer	[1]	(11)	0
AFS Fixed Income Securities [Member] | Corporate Securities [Member]
AFS Fair Value, Less than 12 months		242,392	761,479
AFS Unrealized Losses, Less than 12 months	[1]	(4,315)	(12,671)
AFS Fair Value, 12 months or longer		53,418	50,382
AFS Unrealized Losses, 12 months or longer	[1]	(2,100)	(2,850)
AFS Fixed Income Securities [Member] | Asset-Backed Securities [Member]
AFS Fair Value, Less than 12 months		73,110	197,477
AFS Unrealized Losses, Less than 12 months	[1]	(147)	(807)
AFS Fair Value, 12 months or longer		5,900	12,022
AFS Unrealized Losses, 12 months or longer	[1]	(20)	(111)
AFS Fixed Income Securities [Member] | Commercial Mortgage Backed Securities [Member]
AFS Fair Value, Less than 12 months		24,891	146,944
AFS Unrealized Losses, Less than 12 months	[1]	(82)	(2,196)
AFS Fair Value, 12 months or longer		27,310	15,385
AFS Unrealized Losses, 12 months or longer	[1]	(127)	(214)
AFS Fixed Income Securities [Member] | Residential Mortgage Backed Securities [Member]
AFS Fair Value, Less than 12 months		11,302	264,914
AFS Unrealized Losses, Less than 12 months	[1]	(112)	(1,992)
AFS Fair Value, 12 months or longer		91,548	63,395
AFS Unrealized Losses, 12 months or longer	[1]	(753)	(1,721)
Equity Securities [Member]
AFS Fair Value, Less than 12 months		5,940	32,679
AFS Unrealized Losses, Less than 12 months	[1]	(325)	(2,038)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	0	0
Common Stock [Member] | Equity Securities [Member]
AFS Fair Value, Less than 12 months		5,940	31,148
AFS Unrealized Losses, Less than 12 months	[1]	(325)	(1,998)
AFS Fair Value, 12 months or longer		0	0
AFS Unrealized Losses, 12 months or longer	[1]	$ 0	0
Preferred Stock [Member] | Equity Securities [Member]
AFS Fair Value, Less than 12 months			1,531
AFS Unrealized Losses, Less than 12 months	[1]		(40)
AFS Fair Value, 12 months or longer			0
AFS Unrealized Losses, 12 months or longer	[1]		$ 0
[1] Gross unrealized losses include non-OTTI unrealized amounts and OTTI losses recognized in AOCI. In addition, this column includes remaining unrealized gain or loss amounts on securities that were transferred to an HTM designation in the first quarter of 2009 for those securities that are in a net unrealized/unrecognized loss position.

X

- Definition

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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+ References

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