Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests
Beginning Balances at Dec. 31, 2011	$ 1,117,952	$ 87	$ 361,715	$ 745,658	$ 418	$ 10,074
Beginning Balances, shares at Dec. 31, 2011		86,796
Net income (excludes $962 and $1,555 in 2012, $1,233 and $2,003 in 2013 and $1,210 and $1,625 in 2014 related to redeemable and mandatorily redeemable noncontrolling interests, respectively)	48,199			45,551		2,648
Other comprehensive income	1,429				1,429
Distribution to noncontrolling interests	(1,832)					(1,832)
Share-based compensation	14,087		14,087
Issuance of common stock under stock incentive plans, shares		1,506
Issuance of common stock under stock incentive plans	9,533	1	9,532
Issuance of common stock for acquisitions, shares		473
Issuance of common stock for acquisitions, value	10,500		10,500
Stock repurchases, shares		(403)
Stock repurchases, value	(8,216)		(8,216)
Excess tax benefit from stock based compensation	2,868		2,868
Tax shortfall and other from stock options and awards	(127)		(127)
Ending Balances at Dec. 31, 2012	1,194,393	88	390,359	791,209	1,847	10,890
Ending Balances, shares at Dec. 31, 2012		88,372
Net income (excludes $962 and $1,555 in 2012, $1,233 and $2,003 in 2013 and $1,210 and $1,625 in 2014 related to redeemable and mandatorily redeemable noncontrolling interests, respectively)	139,686			137,511		2,175
Other comprehensive income	(7,999)
Other comprehensive income (excludes $44 and $469 related to mandatorily redeemable noncontrolling interests in 2013 and 2014, respectively)	(8,043)				(8,037)	(6)
Formation of noncontrolling interests	3,336					3,336
Distribution to noncontrolling interests	(1,886)					(1,886)
Purchase of noncontrolling interests	(5,094)		(785)			(4,309)
Share-based compensation	14,104		14,104
Issuance of common stock under stock incentive plans, shares		1,559
Issuance of common stock under stock incentive plans	17,233	2	17,231
Issuance of common stock for acquisitions, value	0
Stock repurchases, shares		(1,423)
Stock repurchases, value	(39,367)	(1)	(39,366)
Excess tax benefit from stock based compensation	3,446		3,446
Tax shortfall and other from stock options and awards	(268)		(268)
Other	76		76
Ending Balances at Dec. 31, 2013	1,317,616	89	384,797	928,720	(6,190)	10,200
Ending Balances, shares at Dec. 31, 2013		88,508
Net income (excludes $962 and $1,555 in 2012, $1,233 and $2,003 in 2013 and $1,210 and $1,625 in 2014 related to redeemable and mandatorily redeemable noncontrolling interests, respectively)	137,848			135,438		2,410
Other comprehensive income	(13,963)
Other comprehensive income (excludes $44 and $469 related to mandatorily redeemable noncontrolling interests in 2013 and 2014, respectively)	(13,494)				(13,207)	(287)
Formation of noncontrolling interests	933					933
Distribution to noncontrolling interests	(2,281)					(2,281)
Purchase of noncontrolling interests	30		30
Share-based compensation	17,200		17,200
Issuance of common stock under stock incentive plans, shares		881
Issuance of common stock under stock incentive plans	2,859		2,859
Issuance of common stock for acquisitions, value	0
Stock repurchases, shares		(6,452)
Stock repurchases, value	(255,108)	(6)	(255,102)
Excess tax benefit from stock based compensation	6,241		6,241
Tax shortfall and other from stock options and awards	(223)		(223)
Ending Balances at Dec. 31, 2014	$ 1,211,621	$ 83	$ 155,802	$ 1,064,158	$ (19,397)	$ 10,975
Ending Balances, shares at Dec. 31, 2014		82,937