Income Taxes Deferred Income Taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred Income Taxes and Other Assets [Abstract]
Accrued expenses	$ 18,957	$ 13,913
Allowance for doubtful accounts	12,313	8,324
Tax credits	3,439	3,375
Insurance	5,814	6,477
Total deferred tax assets	40,523	32,089
State taxes	(420)	(670)
Depreciation and amortization	(14,773)	(6,590)
Prepaid expenses	(4,478)	(2,705)
Total deferred tax liabilities	(19,671)	(9,965)
Net deferred tax assets	$ 20,852	$ 22,124