Statements of Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (loss) [Member]	Total Equity
Balance at Dec. 31, 2012		$ 2,500	$ 893,336	$ 200,754	$ 147,287	$ 1,243,877
Affiliated asset transfers		0	8,086	0	0	8,086
Distribution to parent	184,000	0	0	(184,000)	0	(184,000)
Comprehensive income:
Net income	691,354	0	0	691,354	0	691,354
Other comprehensive income (loss), net of tax	(67,743)	0	0	0	(67,743)	(67,743)
Total comprehensive income (loss)						623,611
Balance at Sep. 30, 2013		2,500	901,422	708,108	79,544	1,691,574
Balance at Dec. 31, 2012		2,500	893,336	200,754	147,287	1,243,877
Comprehensive income:
Other comprehensive income (loss), net of tax
Total comprehensive income (loss)
Balance at Dec. 31, 2013		2,500	901,422	764,846	70,867	1,739,635
Distribution to parent	267,000	0	0	(267,000)	0	(267,000)
Comprehensive income:
Net income	230,966	0	0	230,966	0	230,966
Other comprehensive income (loss), net of tax	12,077	0	0	0	12,077	12,077
Total comprehensive income (loss)						243,043
Balance at Sep. 30, 2014		$ 2,500	$ 901,422	$ 728,812	$ 82,944	$ 1,715,678