Income Taxes Unrecognized tax benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
Reductions based on tax positions related to current year	$ (654)	$ (206)	$ (2,280)
Additions for tax positions of prior years	415	735	6,688
Reductions for tax positions of prior years	(11,917)	(488)	(368)
Settlements	0	(996)	(444)
Unrecognized tax benefit balance	24,208	$ 36,364	$ 37,319	$ 33,723
Tax benefits, if recognized, affect annual effective tax rate	5,000
Unrecognized tax benefits, potential reduction	18,700
Accrued for payment of interest related to unrecognized tax benefits	3,100
Interest expense related to unrecognized tax benefits	$ 346