| Comprehensive income | | | | | | | | | | | | | | | | | | | | | | Three Months Ended
September 30, | | Nine Months Ended
September 30, | | | | | | | | | | | | | | | | | | | | 2011 | | 2010 | | 2011 | | 2010 | | | | | | (In millions) | | | Net income | | $ | 269 | | $ | 161 | | $ | 471 | | $ | 501 | | | Unrealized gain (loss) on investments, net of tax of $1 and ($1) for the three and nine-month periods ended September 30, 2011, respectively, and net of tax of $1 for the nine-month period ended September 30, 2010 | | | (2) | | | — | | | 2 | | | (2) | | | | Total comprehensive income | | $ | 267 | | $ | 161 | | $ | 473 | | $ | 499 | | | | | | | | | | | | | | | | |
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