Schedule III - Supplementary Insurance Information (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013
Supplementary Insurance Information, by Segment [Line Items]
Deferred acquisition costs		$ (3,150,934)		$ (2,957,740)	$ (3,128,931)
Future policy benefits and expenses		9,466,694		9,483,672	8,646,572
Unearned premiums		(6,423,720)		(6,529,675)	(6,662,672)
Claims and benefits payable		3,896,719		3,698,606	3,389,371
Premium revenue		8,350,997		8,632,142	7,759,796
Net investment income		626,217		656,429	650,296
Benefits claims, losses and settlement expenses		4,742,535		4,405,333	3,675,532
Amortization of deferred acquisition costs		1,394,259		1,477,581	1,461,845
Other operating expenses	[1]	3,932,403		3,696,207	3,042,846
Property and Casualty premiums written		2,422,042		3,130,318	3,203,239
Solutions
Supplementary Insurance Information, by Segment [Line Items]
Deferred acquisition costs		(3,148,081)		(3,032,315)	(2,902,868)
Future policy benefits and expenses		5,234,257		5,208,223	5,076,507
Unearned premiums		(5,086,399)		(4,957,688)	(4,801,495)
Claims and benefits payable		283,236		296,545	295,970
Premium revenue		3,015,846		3,128,868	2,783,758
Net investment income		376,683		382,640	376,245
Benefits claims, losses and settlement expenses		919,403		1,027,469	895,504
Amortization of deferred acquisition costs		1,070,237		1,098,911	1,123,856
Other operating expenses	[1]	1,912,026		1,731,147	1,350,403
Property and Casualty premiums written		566,991		760,878	621,543
Specialty Property
Supplementary Insurance Information, by Segment [Line Items]
Deferred acquisition costs		(134,035)		(170,973)	(190,331)
Future policy benefits and expenses		2,089		2,357	2,657
Unearned premiums		(1,382,668)		(1,597,898)	(1,682,960)
Claims and benefits payable		525,406		525,754	490,422
Premium revenue		2,044,701		2,506,097	2,380,044
Net investment income		92,859		101,908	98,935
Benefits claims, losses and settlement expenses		788,549		1,085,339	890,409
Amortization of deferred acquisition costs		280,492		343,314	309,332
Other operating expenses	[1]	1,010,445		961,971	758,941
Property and Casualty premiums written		1,855,051		2,369,440	2,581,696
Employee Benefits
Supplementary Insurance Information, by Segment [Line Items]
Deferred acquisition costs		(33,475)		(25,669)	(23,247)
Future policy benefits and expenses		32,763		31,788	32,025
Unearned premiums		(9,331)		(8,876)	(12,296)
Claims and benefits payable		1,432,045		1,474,805	1,513,013
Premium revenue		1,066,754		1,051,725	1,014,587
Net investment income		110,998		117,192	117,853
Benefits claims, losses and settlement expenses		730,192		716,892	715,656
Amortization of deferred acquisition costs		32,836		30,786	27,856
Other operating expenses	[1]	365,921		368,763	360,303
Property and Casualty premiums written		0		0	0
Health
Supplementary Insurance Information, by Segment [Line Items]
Deferred acquisition costs		0		(19,652)	(12,485)
Future policy benefits and expenses		78,723		88,411	95,380
Unearned premiums		(29,607)		(137,546)	(136,376)
Claims and benefits payable		552,950		391,611	239,733
Premium revenue		2,223,696		1,945,452	1,581,407
Net investment income		24,487		35,369	36,664
Benefits claims, losses and settlement expenses		2,301,241		1,575,633	1,169,075
Amortization of deferred acquisition costs		10,694		4,570	801
Other operating expenses	[1]	516,726		491,248	434,749
Property and Casualty premiums written		0		0	0
Corporate & Other
Supplementary Insurance Information, by Segment [Line Items]
Deferred acquisition costs		(164,657)	[2]	(290,869)	0
Future policy benefits and expenses		4,118,862	[2]	4,152,893	3,440,003
Unearned premiums		84,285	[2]	172,333	(29,545)
Claims and benefits payable		1,103,082	[2]	1,009,891	850,233
Premium revenue		0	[2]	0	0
Net investment income		21,190	[2]	19,320	20,599
Benefits claims, losses and settlement expenses		3,150	[2]	0	4,888
Amortization of deferred acquisition costs		0	[2]	0	0
Other operating expenses	[1]	127,285	[2]	143,078	138,450
Property and Casualty premiums written		$ 0	[2]	$ 0	$ 0

[1] Includes amortization of value of business acquired and underwriting, general and administration expenses.

[2] Amounts related to deferred acquisition costs and unearned premiums are impacted by the adjustment described in Note 2 - Use of Estimates section.