Schedule II Condensed Cash Flows (Parent Only) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Condensed Financial Statements, Captions [Line Items]
Net income	$ 49,755	$ 140,297	$ 143,610	$ 137,245	$ 108,816	$ 128,788	$ 133,523	$ 117,780	$ 470,907		$ 488,907		$ 483,705
Change in accounts payable and other liabilities									266,648		181,374		33,775
Change in securities classified as trading									(23,782)		(10,606)		(2,874)
Change in income taxes									62,087		171,311		(5,800)
Change in tax valuation allowance									1,690		3,383		2,937
Depreciation and amortization									132,217		124,851		124,387
Loss on extinguishment of debt									0		964		0
Stock based compensation expense									49,354		50,004		37,589
Change in tax benefit from share-based payment arrangements									(14,900)		1,112		(1,728)
Other									(51,000)		(35,082)		13,738
Net cash provided by operating activities									393,816		1,027,561		679,698
Fixed maturity securities available for sale									1,887,983		2,582,731		2,197,475
Equity securities available for sale									109,233		236,730		120,729
Other invested assets									74,257		49,456		103,834
Property and equipment and other									172		1,422		2,375
Subsidiary									0	[1]	0	[1]	1,364	[1]
Fixed maturity securities available for sale									(2,472,494)		(3,396,588)		(3,729,316)
Equity securities available for sale									(132,748)		(215,881)		(186,962)
Other invested assets									(41,653)		(57,001)		(41,640)
Property and equipment and other									(83,603)		(52,326)		(56,457)
Subsidiary									(149,194)	[1]	(181,865)	[1]	(3,500)	[1]
Change in short-term investments									93,571		(173,603)		140,309
Net cash provided by (used in) investing activities									63,889		(392,738)		(449,883)
Issuance of debt									0		698,093		0
Repurchase of debt									0		(33,634)		0
Repayment of debt									(467,330)		0		0
Change in tax benefit from share-based payment arrangements									14,900		(1,112)		1,728
Acquisition of common stock									(215,183)		(393,012)		(412,196)
Dividends paid									(77,495)		(74,128)		(69,393)
Net cash (used in) provided by financing activities									(776,199)		196,699		(480,641)
Effect of exchange rate changes on cash and cash equivalents									(28,126)		(23,742)		(6,483)
Change in cash and cash equivalents									(398,528)		807,780		(257,309)
Cash and cash equivalents	1,318,656				1,717,184				1,318,656		1,717,184		909,404		1,166,713
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income									470,907		488,907		483,705
Equity in undistributed net income of subsidiaries									(584,464)		(628,894)		(601,356)
Dividends received from subsidiaries									505,225		446,592		524,508
Change in receivables									(5,075)		(4,609)		(1,035)
Change in accrued interest									(9,852)		5,941		0
Change in accounts payable and other liabilities									(16,146)		57,229		19,330
Change in securities classified as trading									(7,309)		(9,600)		(6,862)
Change in income taxes									2,732		18,159		10,903
Change in tax valuation allowance									0		0		(682)
Depreciation and amortization									32,094		34,047		34,471
Net realized gains on investments									(4,288)		(1,763)		(7,464)
Loss on extinguishment of debt									0		964		0
Stock based compensation expense									49,354		50,004		37,589
Change in tax benefit from share-based payment arrangements									(14,900)		1,112		(1,728)
Other									(20,613)		(17,491)		(11,034)
Net cash provided by operating activities									397,665		440,598		480,345
Fixed maturity securities available for sale									444,589		394,997		404,548
Equity securities available for sale									8,895		19,315		11,756
Property and equipment and other									0		41		552
Subsidiary									0		0		2,231
Fixed maturity securities available for sale									45,145		69,156		78,151
Fixed maturity securities available for sale									(253,866)		(314,864)		(793,938)
Equity securities available for sale									(9,433)		(15,557)		(17,329)
Other invested assets									(4,134)		(152)		(1)
Property and equipment and other									(49,569)		(29,635)		(40,750)
Subsidiary									0		0		(3,500)
Capital contributed to subsidiaries									(453,700)		(323,600)		(9,000)
Return of capital contributions from subsidiaries									205,250		174,277		67,500
Change in short-term investments									115,856		(118,123)		(255)
Net cash provided by (used in) investing activities									49,033		(144,145)		(300,035)
Issuance of debt									0		698,093		0
Repurchase of debt									0		(33,634)		0
Repayment of debt									(467,330)		0		0
Change in tax benefit from share-based payment arrangements									14,900		(1,112)		1,728
Acquisition of common stock									(215,183)		(393,012)		(412,196)
Dividends paid									(77,495)		(74,128)		(69,393)
Net cash (used in) provided by financing activities									(745,108)		196,207		(479,861)
Effect of exchange rate changes on cash and cash equivalents									50		(49)		0
Change in cash and cash equivalents									(298,360)		492,611		(299,551)
Cash and cash equivalents	$ 392,189				$ 690,549				$ 392,189		$ 690,549		$ 197,938		$ 497,489

[1] 2014 includes the acquisition of StreetLinks, LLC, eMortgage Logic, LLC, CWI Group and other immaterial subsidiaries. 2013 includes the acquisition of Field Asset Services Group Limited and Lifestyle Services Group Limited. 2012 includes the sale of one immaterial subsidiary.