Consolidated Statements Of Changes In Stockholder's Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss), Net Of Deferred Income Taxes [Member]	Retained Earnings [Member]	Total
Balance, beginning of period, shares at Dec. 31, 2013	1,000
Balance, beginning of period at Dec. 31, 2013		$ 351,051	$ 87,648	$ 3,751,779
Share-based compensation plans		8,939
Net increase (decrease) during the period			8,916		$ 8,916
Net income (loss)				344,781	344,781
Balance, end of period, shares at Sep. 30, 2014	1,000
Balance, end of period at Sep. 30, 2014		359,990	96,564	4,096,560	4,553,114
Balance, beginning of period, shares at Jun. 30, 2014	1,000
Balance, beginning of period at Jun. 30, 2014		357,537	130,128	3,996,419
Share-based compensation plans		2,453
Net increase (decrease) during the period			(33,564)		(33,564)
Net income (loss)				100,141	100,141
Balance, end of period, shares at Sep. 30, 2014	1,000
Balance, end of period at Sep. 30, 2014		359,990	96,564	4,096,560	$ 4,553,114
Balance, beginning of period, shares at Dec. 31, 2014	1,000				1,000
Balance, beginning of period at Dec. 31, 2014		362,293	4,519	4,205,905	$ 4,572,717
Share-based compensation plans		10,273
Net increase (decrease) during the period			(40,782)		(40,782)
Net income (loss)				245,051	$ 245,051
Balance, end of period, shares at Sep. 30, 2015	1,000				1,000
Balance, end of period at Sep. 30, 2015		372,566	(36,263)	4,450,956	$ 4,787,259
Balance, beginning of period, shares at Jun. 30, 2015	1,000
Balance, beginning of period at Jun. 30, 2015		369,284	7,907	4,455,615
Share-based compensation plans		3,282
Net increase (decrease) during the period			(44,170)		(44,170)
Net income (loss)				(4,659)	$ (4,659)
Balance, end of period, shares at Sep. 30, 2015	1,000				1,000
Balance, end of period at Sep. 30, 2015		$ 372,566	$ (36,263)	$ 4,450,956	$ 4,787,259