Consolidated Statements of Shareholder's Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]
Balance at beginning of period (shares) at Dec. 31, 2012		500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (shares)		2
Balance at end of period (shares) at Dec. 31, 2013		502
Balance at beginning of period at Dec. 31, 2012		$ 0	$ 3,459	$ (3)	$ 923
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued		0
Stock-based compensation expense			10
Capital contributions from related party			1,300
Differences between tax payments due under consolidated return and separate return basis			16
Other comprehensive (loss) income, net				14
Net income	$ 566				566
Balance at end of period at Dec. 31, 2013		$ 0	4,785	11	1,489
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (shares)		3
Balance at end of period (shares) at Dec. 31, 2014		505
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued		$ 0
Stock-based compensation expense			18
Capital contributions from related party			996
Differences between tax payments due under consolidated return and separate return basis			0
Other comprehensive (loss) income, net				(444)
Net income	537				537
Balance at end of period at Dec. 31, 2014	7,392	$ 0	5,799	(433)	2,026
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued (shares)		0
Balance at end of period (shares) at Dec. 31, 2015		505
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued		$ 0
Stock-based compensation expense			35
Capital contributions from related party			649
Differences between tax payments due under consolidated return and separate return basis			1
Other comprehensive (loss) income, net				(671)
Net income	646				646
Balance at end of period at Dec. 31, 2015	$ 8,052	$ 0	$ 6,484	$ (1,104)	$ 2,672