Accumulated Other Comprehensive Income (Reclassification out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016		Jun. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on investments, excluding other-than-temporary impairment losses		$ 21,679	$ 11,999	$ 184,045	[1]	$ 18,524
Portion of net (gain) loss recognized in other comprehensive income, before taxes		0	0	(337)		638
Provision for income taxes		(66,163)	(7,236)	(183,352)		(40,385)
Net income		169,349	32,789	389,667		82,833
Unrealized gains on securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax		(4,335)	(6,542)	(100,469)		(10,478)
OTTI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax		34	(376)	315		1,295
Pension under- funding
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax		406	2,616	(18,413)		5,233
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax		(3,895)	(4,302)	(118,567)		(3,950)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains on securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net realized gains on investments, excluding other-than-temporary impairment losses		(6,669)	(10,064)	(154,567)		(16,120)
Provision for income taxes		2,334	3,522	54,098		5,642
Net income		(4,335)	(6,542)	(100,469)		(10,478)
Reclassification out of Accumulated Other Comprehensive Income | OTTI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Portion of net (gain) loss recognized in other comprehensive income, before taxes		53	(578)	485		1,992
Provision for income taxes		(19)	202	(170)		(697)
Net income		34	(376)	315		1,295
Reclassification out of Accumulated Other Comprehensive Income | Pension under- funding
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		625	4,025	(28,328)		8,050
Provision for income taxes		(219)	(1,409)	9,915		(2,817)
Total reclassifications for the period, net of tax		406	2,616	(18,413)		5,233
Reclassification out of Accumulated Other Comprehensive Income | Amortization of prior service cost
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	[2]	0	(25)	0		(50)
Reclassification out of Accumulated Other Comprehensive Income | Amortization of net loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	[2]	$ 625	$ 4,050	1,250		8,100
Reclassification out of Accumulated Other Comprehensive Income | Gain on pension plan curtailment
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax				$ (29,578)		$ 0

[1] Six months ended June 30, 2016 net gains includes $146,727 related to the sale of Assurant Employee Benefits as described in Note 5.

[2] These accumulated other comprehensive income components are included in the computation of net periodic pension cost. See Note 14 - Retirement and Other Employee Benefits for additional information.