Earnings Per Share (Narrative) (Details) - Telesat Holdings Inc [Member]	9 Months Ended
Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2015
Equity Method Investment Economic Ownership Percentage	62.70%	62.70%	62.80%
Percentage of economic interest as result of dilution upon exercise of stock options	62.20%

The percentage of economic ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

No definition available.

Name:	lorl_EquityMethodInvestmentEconomicOwnershipPercentage
Namespace Prefix:	lorl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant