Income Taxes - Uncertain Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in unrecognized tax benefits
Balance at beginning of year	$ 8,269	$ 7,452	$ 9,152
Additions for tax positions related to current year	2,154	511	1,038
Additions for tax positions relating to prior years	1,721	3	233
Reductions for tax positions relating to prior years	(934)	(4,877)	(2,826)
Reductions due to the lapse of the applicable statute of limitations	(26)	(122)	(39)
Settlements	(47)	(287)	(106)
Additions for business combination		5,589
Balance at end of year	11,137	8,269	$ 7,452
Unrecognized tax benefits that would impact effective tax rate if recognized	1,500
Accrued interest and penalties related to unrecognized tax benefits	$ 300	$ 300

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Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of increase in unrecognized tax benefits resulting from acquisitions.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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