Subsequent Events	12 Months Ended
Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTSOn February 12, 2019, the Company announced that its board of directors authorized a new $125 million anti-dilutive stock repurchase program (the "2019 Program") following the completion of its $125 million repurchase program authorized in July 2018. Under the 2019 Program, IPG management is authorized to repurchase shares of common stock in an amount not to exceed the lesser of (a) the number of shares issued to employees and directors under the Company's various employee and director equity compensation and employee stock purchase plans from January 1, 2019 through December 31, 2020 and (b) $125 million, exclusive of any fees, commissions or other expenses. Share repurchases will be made periodically in open-market transactions using the Company's working capital, and are subject to market conditions, legal requirements and other factors. The 2019 Program authorization does not obligate the Company to repurchase any dollar amount or number of its shares, and repurchases may be commenced or suspended from time to time without prior notice.

Subsequent Events

12 Months Ended

Dec. 31, 2018

SUBSEQUENT EVENTSOn February 12, 2019, the Company announced that its board of directors authorized a new $125 million anti-dilutive stock repurchase program (the "2019 Program") following the completion of its $125 million repurchase program authorized in July 2018. Under the 2019 Program, IPG management is authorized to repurchase shares of common stock in an amount not to exceed the lesser of (a) the number of shares issued to employees and directors under the Company's various employee and director equity compensation and employee stock purchase plans from January 1, 2019 through December 31, 2020 and (b) $125 million, exclusive of any fees, commissions or other expenses. Share repurchases will be made periodically in open-market transactions using the Company's working capital, and are subject to market conditions, legal requirements and other factors. The 2019 Program authorization does not obligate the Company to repurchase any dollar amount or number of its shares, and repurchases may be commenced or suspended from time to time without prior notice.