Income Taxes (Schedule Of Components Of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Current, Federal									$ 22,914	$ 1,968	$ 37,960
Deferred, Federal									81,267	70,583	7,722
Total, Federal									104,181	72,551	45,682
Current, State									1,708	1,045	8,187
Deferred, State									18,699	9,444	323
State, Total									20,407	10,489	8,510
Current Income Tax Expense (Benefit)									24,622	3,013	46,147
Deferred income tax expense									99,966	80,027	8,045
Income Tax Expense (Benefit)	$ 35,704	$ 31,633	$ 30,612	$ 26,639	$ 29,641	$ 32,107	$ 11,356	$ 9,936	$ 124,588	$ 83,040	$ 54,192