Condensed Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
REVENUE	$ 582,397	$ 571,891	$ 1,153,176	$ 1,137,381
COST OF SERVICES	249,426	245,266	490,438	484,967
SELLING, GENERAL AND ADMINISTRATIVE EXPENSES	209,870	210,192	430,713	425,288
OPERATING INCOME	123,101	116,433	232,025	227,126
OTHER INCOME (EXPENSE):
Interest expense, net of interest income of $20, $173, $290 and $199	(37,712)	(38,433)	(76,195)	(77,275)
Accelerated amortization of deferred financing costs	(35,235)	0	(35,235)	0
Other, net	1,214	(100)	174	3,739
Other expense	(71,733)	(38,533)	(111,256)	(73,536)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAX EXPENSE	51,368	77,900	120,769	153,590
INCOME TAX EXPENSE ATTRIBUTED TO CONTINUING OPERATIONS	18,389	28,677	43,235	55,733
INCOME FROM CONTINUING OPERATIONS	32,979	49,223	77,534	97,857
INCOME FROM DISCONTINUED OPERATIONS, NET OF INCOME TAXES	0	358	0	32,224
NET INCOME	$ 32,979	$ 49,581	$ 77,534	$ 130,081
EARNINGS PER COMMON SHARE—BASIC:
Continuing Operations	$ 0.40	$ 0.59	$ 0.94	$ 1.17
Discontinued Operations	0	0	0	0.38
Total Earnings Per Common Share—Basic	0.40	0.59	0.94	1.55
EARNINGS PER COMMON SHARE—DILUTED:
Continuing Operations	0.39	0.58	0.92	1.14
Discontinued Operations	0	0	0	0.37
Total Earnings Per Common Share—Diluted	$ 0.39	$ 0.58	$ 0.92	$ 1.51
WEIGHTED AVERAGE NUMBER OF SHARES OUTSTANDING:
Basic Common	82,598	83,394	82,874	83,758
Diluted Common	84,281	85,592	84,425	85,920
DIVIDENDS DECLARED:
Dividends declared per share	$ 0.225	$ 0.225	$ 0.45	$ 0.45