Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 649,603us-gaap_ProfitLoss	$ 505,301us-gaap_ProfitLoss	$ 510,643us-gaap_ProfitLoss
Other comprehensive income:
Change in unrealized translation adjustments	(62,125)	(23,848)	24,563
Change in unrealized investment gains (losses), net of taxes	49,666	(261,064)	87,316
Change in unrecognized pension obligation, net of taxes	6,651	8,700	(1,022)
Other comprehensive income (loss)	(5,808)	(276,212)	110,857
Comprehensive income	643,795	229,089	621,500
Comprehensive income to the noncontrolling interest	(752)	(5,404)	(128)
Comprehensive income to common shareholders	$ 643,043us-gaap_ComprehensiveIncomeNetOfTax	$ 223,685us-gaap_ComprehensiveIncomeNetOfTax	$ 621,372us-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.

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

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Amount after tax of (increase) decrease in the value of the projected benefit obligation related to a change in an actuarial assumption and increase (decrease) in the value of the plan assets resulting from experience different from that assumed, that has not been recognized in net periodic benefit (cost) credit.

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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 and reclassification adjustments of other comprehensive income (loss).

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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