Income Taxes - Income tax rate reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Statutory federal income tax rate	21.00%	21.00%	35.00%
Non-deductibility of goodwill impairment	0.00%	0.00%	(29.30%)
Change in federal tax rate	0.00%	0.00%	15.50%
State and other taxes, net of federal tax benefit	2.80%	3.60%	0.40%
Change in unrecognized tax benefits	1.80%	3.30%	(0.70%)
Change in valuation allowance	0.50%	0.40%	0.30%
Domestic production activity deduction	0.00%	0.00%	0.30%
Changes in tax rates and state tax laws	(0.50%)	(1.60%)	(0.30%)
Change in accounting for excess tax deficiencies/benefits	(0.60%)	0.10%	(0.50%)
Effective Income Tax Rate Reconciliation, Other Reconciling Items, Amount	(1.30%)	(0.20%)	(0.00%)
Other	0.90%	0.80%	(0.70%)
Effective tax rate	24.60%	27.40%	20.00%