Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 100	$ 100
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized shares	600,000,000.0us-gaap_CommonStockSharesAuthorized	600,000,000.0us-gaap_CommonStockSharesAuthorized
Common stock, issued shares	220,500,000us-gaap_CommonStockSharesIssued	255,500,000us-gaap_CommonStockSharesIssued
Common stock, outstanding shares	219,800,000us-gaap_CommonStockSharesOutstanding	254,500,000us-gaap_CommonStockSharesOutstanding

Face amount or stated value per share of common stock.

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