Income Taxes - Changes in Unrecognized Tax Benefit (Including Interest and Penalties) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 12,683	$ 5,711	$ 3,658
Additions for tax positions for current year	4,171	3,141	793
Additions for tax positions for prior years	1,454	4,132	1,593
Reduction for tax positions for prior years	(2,108)	(224)	(287)
Lapse of the applicable statute of limitations	(521)	(77)	(46)
Reduction as a result of settlement	(1,540)
Ending Balance	14,139	12,683	5,711
Unrecognized Tax Benefits Before Interest And Penalties
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	11,505	5,269	3,357
Additions for tax positions for current year	4,171	3,141	793
Additions for tax positions for prior years	631	3,378	1,427
Reduction for tax positions for prior years	(1,865)	(223)	(271)
Lapse of the applicable statute of limitations	(435)	(60)	(37)
Reduction as a result of settlement	(1,318)
Ending Balance	12,689	11,505	5,269
Interest & Penalties
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	1,178	442	301
Additions for tax positions for current year	0	0	0
Additions for tax positions for prior years	823	754	166
Reduction for tax positions for prior years	(243)	(1)	(16)
Lapse of the applicable statute of limitations	(86)	(17)	(9)
Reduction as a result of settlement	(222)
Ending Balance	$ 1,450	$ 1,178	$ 442