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Earnings Per Share (Computation Of Basic And Diluted Earnings Per Share) (Detail) - USD ($) $ / shares in Units, $ in Millions | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Basic earnings per share: [Abstract] |  |  |  |
Net income (loss) |  | $ (338) | $ 180 | $ 569
Less: Undistributed earnings allocated to participating securities |  | 0 | 6 | 16
Net income (loss) available to common stockholders |  | $ (338) | $ 174 | $ 553
Basic weighted average shares | [1] | 133,001,088 | 163,936,318 | 188,171,503
Basic |  | $ (2.54) | $ 1.06 | $ 2.94
Diluted earnings per share: [Abstract] |  |  |  |
Net income (loss) |  | $ (338) | $ 180 | $ 569
Less: Undistributed earnings allocated to participating securities |  | 0 | 6 | 15
Less: mark-to-market gain (loss) on warrants |  | 0 | 0 | 28
Net income (loss) available to common stockholders |  | $ (338) | $ 174 | $ 526
Basic weighted average shares | [1] | 133,001,088 | 163,936,318 | 188,171,503
Stock options |  | 0 | 933,470 | 1,104,247
Warants |  | 0 | 0 | 1,622,877
Diluted weighted average shares |  | 133,001,088 | 164,869,788 | 190,898,627
Diluted |  | $ (2.54) | $ 1.06 | $ 2.76
Unvested Restricted Stock And Units That Receive Nonforfeitable Dividends Or Dividend Equivalents That Have Met Service Condition |  | 930,406 | 617,909 | 412,769
[1] | Includes 930,406, 617,909 and 412,769 of participating securities that met the service condition and were eligible to receive nonforfeitable dividends or dividend equivalents for the years ended December 31, 2016, 2015 and 2014, respectively.

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- Definition The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.21) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 55 -Paragraph 52 -URI http://asc.fasb.org/extlink&oid=32703322&loc=d3e4984-109258 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=7655603&loc=d3e1252-109256 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.19) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.23) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 18 -Article 7 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 20 -Article 5 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 21 -Article 9 + Details
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