Accumulated Other Comprehensive Loss (Summary of Activity in Accumulated Other Comprehensive Loss attributable to Navigant, Consulting Inc.) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ 708,564
Balance	659,237
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	(6,529)	$ (19,308)
Unrealized (loss) gain	(442)	1,369
Balance	(6,971)	(17,939)
Accumulated Net Loss from Cash Flow Hedges Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance		130
Unrealized (loss) gain		250
Reclassified to interest expense		10
Income tax expense		(3)
Balance		387
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance	$ (6,971)	$ (17,552)