Income Taxes (Reconciliation of Provision (Benefit) for Income Taxes) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Provision (Benefit) for Income Taxes
Federal income expense (benefit) at statutory tax rate	$ 65,603	$ 48,865	$ (93,745)
State income taxes, net of federal tax benefit	10,367	6,236	3,214
Officers' compensation	3,657	1,732	1,473
Domestic Production Activities Deduction	(5,170)	(3,641)	(2,246)
Goodwill Impairment			89,191
Impact of state tax rate changes on deferreds	3,245
Other	1,800	(873)	(329)
Total (benefit) provision	$ 79,502	$ 52,319	$ (2,442)
Reconciliation of Effective Income Tax Rate
Federal income expense (benefit) at statutory tax rate (in hundredths)	35.00%	35.00%	35.00%
State income taxes, net of federal tax benefit (in hundredths)	5.50%	4.50%	(1.20%)
Officers' compensation (in hundredths)	2.00%	1.20%	(0.60%)
Domestic Production Activities Deduction (in hundredths)	(2.80%)	(2.60%)	(2.40%)
Goodwill impairment (in hundredths)			(33.30%)
Impact of state tax rate changes on deferreds (in hundredths)	1.70%
Other (in hundredths)	1.00%	(0.60%)	3.40%
(Benefit) provision for income taxes (in hundredths)	42.40%	37.50%	0.90%