Earnings Per Share (Narrative) (Details) $ / shares in Units, shares in Thousands, $ in Thousands |
1 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
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Sep. 30, 2009
USD ($)
$ / shares
shares
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Dec. 31, 2017
USD ($)
$ / shares
shares
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Dec. 31, 2016
shares
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Dec. 31, 2015
shares
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Sep. 18, 2014
$ / shares
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| Debt Instrument [Line Items] | |||||
| Undistributed earnings allocated to participating unvested share-based payment awards, weighted outstanding shares | 5,200 | 5,100 | 4,400 | ||
| Exchangeable Surplus Notes (in shares) | 5,800 | 5,700 | 5,500 | ||
| Long-term debt | Exhangeable Surplus Notes | |||||
| Debt Instrument [Line Items] | |||||
| Debt Instrument, Face Amount | $ | $ 500,000 | ||||
| Interest Rate | 5.36% | ||||
| Debt Instrument, Convertible, Conversion Ratio | 10.1235 | 11.7643 | |||
| Surplus notes principal amount, for each | $ | $ 1 | $ 1 | |||
| Exchangeable Surplus Notes (in shares) | 5,100 | 5,880 | |||
| Exchange price of common stock, per share | $ / shares | $ 98.78 | $ 85.00 | $ 102.62 | ||
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- Definition The price per share of the conversion feature embedded in the debt instrument. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Face (par) amount of debt instrument at time of issuance. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Contractual interest rate for funds borrowed, under the debt agreement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible debt securities using the if-converted method. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition This element represents nonvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). Basic and dilutive earnings per share are generally disclosed for such shares using the two-class method. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Financial instruments issued by insurance entities (surplus notes) that are includable in surplus for statutory accounting purposes as prescribed or permitted by state laws and regulations that are liabilities of the issuer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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