Financing Arrangements - Schedule of Term Facility Financial Covenants (Detail) - 2017 Facility	12 Months Ended
Dec. 31, 2018
Q1 2019
Debt Instrument [Line Items]
Debt instrument covenant leverage ratio	4.75
Thereafter
Debt Instrument [Line Items]
Debt instrument covenant leverage ratio	4.50

Represents the net leverage ratio for the covenants. Contains a number of , negative, reporting and financial covenants, in each case subject to certain exceptions and materiality thresholds. Required to be in quarterly compliance, measured on a trailing four quarter basis. contains usual and customary restrictions on the ability of the Company and its subsidiaries to: (i) incur additional indebtedness (ii) create liens; (iii) consolidate, merge, sell or otherwise dispose of all or substantially all of its assets; (iv) sell certain assets; (v) pay dividends on, repurchase or make distributions in respect of capital stock or make other restricted payments; (vi) make certain investments; (vii) repay subordinated indebtedness prior to stated maturity; and (viii) enter into certain transactions with its affiliates.

No definition available.

Name:	lnth_DebtInstrumentCovenantLeverageRatio
Namespace Prefix:	lnth_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration