CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Receivables, allowance for doubtful accounts	$ 41,131	$ 42,409
Other intangible assets, accumulated amortization	$ 156,246	$ 122,283
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, authorized (in shares)	20,000,000	20,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, authorized (in shares)	480,000,000	480,000,000
Common stock, issued (in shares)	179,400,000	179,103,000
Common stock, outstanding (in shares)	137,284,000	139,542,000
Treasury stock (in shares)	42,116,000	39,561,000