CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net income	$ 133,076us-gaap_NetIncomeLoss	$ 59,982us-gaap_NetIncomeLoss
Other comprehensive income, net of tax ( (Note 9):
Change in unrealized investment gains and losses (note 7)	19,563	39,598
Benefit plan adjustments	(700)	(1,486)
Foreign currency translation adjustment	(2,014)	1,253
Other comprehensive income, net of tax	16,849	39,365
Comprehensive income	$ 149,925us-gaap_ComprehensiveIncomeNetOfTax	$ 99,347us-gaap_ComprehensiveIncomeNetOfTax

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Other Comprehensive Income

-URI http://asc.fasb.org/extlink&oid=6519514

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Comprehensive Income

-URI http://asc.fasb.org/extlink&oid=35737396

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

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-Topic 944

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Amount after tax and reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans, attributable to parent entity.

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Amount after tax and reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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