Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
REVENUE	$ 2,291,963	$ 2,280,259	$ 2,218,594
COST OF SERVICES	981,788	970,693	943,331
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	865,961	853,116	813,856
OPERATING INCOME	444,214	456,450	461,407
OTHER INCOME (EXPENSE):
Interest income	348	205	268
Interest expense	(148,627)	(154,273)	(188,102)
Debt call premium and accelerated amortization of deferred financing costs	(36,532)	(2,304)	(73,309)
Other, net	409	(1,405)	7,026
Other expense	(184,402)	(157,777)	(254,117)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAX EXPENSE	259,812	298,673	207,290
INCOME TAX EXPENSE ATTRIBUTED TO CONTINUING OPERATIONS	66,423	107,757	72,679
INCOME FROM CONTINUING OPERATIONS	193,389	190,916	134,611
INCOME FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES	0	50,924	23,794
NET INCOME	$ 193,389	$ 241,840	$ 158,405
EARNINGS PER COMMON SHARE—BASIC:
Continuing Operations	$ 2.33	$ 2.29	$ 1.60
Discontinued Operations	0	0.61	0.29
Total Earnings Per Common Share—Basic	2.33	2.90	1.89
EARNINGS PER COMMON SHARE—DILUTED
Continuing Operations	2.29	2.24	1.57
Discontinued Operations	0	0.59	0.28
Total Earnings Per Common Share—Diluted	$ 2.29	$ 2.83	$ 1.85
WEIGHTED AVERAGE NUMBER OF SHARES OUTSTANDING:
Basic Common	82,969	83,420	84,007
Diluted Common	84,599	85,394	85,507