Commitments and Contingencies - Additional Information (Detail) $ in Millions		6 Months Ended
	Jul. 19, 2017	Jun. 30, 2017 USD ($) Lawsuit
Commitments [Line Items]
Product liability contingency, loss exposure description		There are asserted claims against the Company where an unfavorable outcome is considered to be reasonably possible. These claims can generally be categorized in the following areas: (l) commercial disputes with customers or other business partners, which may involve assertion of a breach of the Company’s legal or contractual obligations to the customer or a claim for indemnification for third-party losses; and (2) other matters which may include issues such as employment related claims.
Alorica Inc. [Member]
Commitments [Line Items]
Discontinued operations, indemnification up to purchase price liability | $		$ 275.0
Subsequent Event [Member]
Commitments [Line Items]
Lawsuit dismissal date	Jul. 19, 2017
Directors [Member] | West and Members of the Board [Member]
Commitments [Line Items]
Number of putative class action lawsuits | Lawsuit		1
Apollo Global Management and Certain Affiliates of Funds Managed by Apollo Global Management, Mount Olympus Holdings, Inc. and Olympus Merger Sub, Inc. [Member] | West and Members of the Board [Member]
Commitments [Line Items]
Number of putative class action lawsuits | Lawsuit		2
Class Action Lawsuits related to Merger Agreement [Member]
Commitments [Line Items]
Domicile of litigation		United States District Court for the District of Nebraska: Scarantino v. West Corp., et al., 4:17-cv-03080-JMG-CRZ (D. Neb.); Wyant v. West Corp., et al., 4:17-cv-03081-JMG-CRZ (D. Neb.); Wilson v. West Corp., et al., 8:17-cv-00228-JMG-CRZ (D. Neb.); Bushansky v. West Corp., et al., 4:17-cv-03083-JMG-CRZ (D. Neb.); and Katz v. West Corp. et al., 4:17-cv-03084-JMG-CRZ (D. Neb.).
Class Action Lawsuits related to Merger Agreement [Member] | West and Members of the Board [Member]
Commitments [Line Items]
Number of putative class action lawsuits | Lawsuit		5
Minimum [Member]
Commitments [Line Items]
Product liability contingency, loss exposure in excess of accrual | $		$ 0.0
Minimum [Member] | Class Action Lawsuits related to Merger Agreement [Member]
Commitments [Line Items]
Lawsuit filing date		June 26, 2017
Maximum [Member]
Commitments [Line Items]
Product liability contingency, loss exposure in excess of accrual | $		$ 24.0
Maximum [Member] | Class Action Lawsuits related to Merger Agreement [Member]
Commitments [Line Items]
Lawsuit filing date		June 29, 2017