Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Face (par) amount of debt instrument at time of issuance.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Contractual interest rate for funds borrowed, under the debt agreement.

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Fair value amount of debt instrument that was repurchased.

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Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

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Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

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Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

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Subsequent Events (Details) - USD ($)			3 Months Ended
Subsequent Events (Details) - USD ($)	Apr. 20, 2016	Apr. 18, 2016	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Feb. 10, 2011
Subsequent Event [Line Items]
Dividends declared per share			$ 0.65	$ 0.62
Subsequent Event
Subsequent Event [Line Items]
Dividends declared per share	$ 0.65
Senior Notes \| 6.00% Senior Notes Due 2026 \| Subsequent Event
Subsequent Event [Line Items]
Senior Notes		$ 350,000,000
Interest rate		6.00%
Debt Issuance Cost		$ 7,000,000
Senior Notes \| 6.625% Senior Notes
Subsequent Event [Line Items]
Senior Notes			$ 300,000,000			$ 300,000,000.0
Interest rate			6.625%		6.625%
Senior Notes \| 6.625% Senior Notes \| Subsequent Event
Subsequent Event [Line Items]
Debt instrument, repurchase amount		231,000,000
Loss on extinguishment of debt		$ 16,000,000
Senior Notes \| 5.125% Senior Notes
Subsequent Event [Line Items]
Interest rate			5.125%		5.125%