Income Taxes (Asset/Liability) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Federal net operating loss capital loss and credit carryforwards	$ 45,259	$ 65,168
Deferred revenue	114,770	137,688
Bad debt reserves	8,483	7,119
Employee benefits	47,479	43,684
Accrued expenses and loss reserves	35,303	29,384
Other	9,877	2,519
Less: valuation allowance	(30,955)	(29,389)
Total deferred tax assets	230,216	256,173
Deferred tax liabilities:
Depreciable and amortizable assets	182,283	186,260
Investment in affiliates	20,457	10,407
Total deferred tax liabilities	202,740	196,667
Net deferred tax asset/(liability)	$ 27,476	$ 59,506