UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions		3 Months Ended
		Mar. 30, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income		$ 208	$ 168
Other comprehensive income:
Foreign currency translation adjustments		33	19
Unrealized gains on hedging instruments		(1)	0
Pension and postretirement benefit plans:
Amortization of net loss and prior service cost previously recognized (1)	[1]	14	9
Total other comprehensive income		46	28
Comprehensive income		254	196
Comprehensive income attributable to noncontrolling interests		(5)	(4)
Comprehensive income attributable to L3		$ 249	$ 192

[1] Net of income taxes of $4 million and $6 million for the quarterly periods ended March 30, 2018 and March 31, 2017, respectively.