Condensed, Consolidated Statements of Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income	Noncontrolling Interests
Beginning Balances (in shares) at Dec. 31, 2015		80,764
Beginning Balances at Dec. 31, 2015	$ 1,257,034	$ 81	$ 19,708	$ 1,275,207	$ (50,034)	$ 12,072
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (excludes $1,300 and $827 during the six months ended June 30, 2016 and $969 and $810 during the six months ended June 30, 2017 related to redeemable and mandatorily redeemable noncontrolling interests, respectively)	112,021			110,277		1,744
Other comprehensive income (excludes $168 for the six months ended June 30, 2016 and $87 for the six months ended June 30, 2017 related to mandatorily redeemable noncontrolling interests)	12,462				12,207	255
Formation of noncontrolling interests	88,949					88,949
Distributions to noncontrolling interests	(1,166)					(1,166)
Purchase of noncontrolling interests (excludes $1,185 related to redeemable noncontrolling interests) in 2017	(3,730)		(1,822)			(1,908)
Share-based compensation	9,104		9,104
Issuance of common stock under stock incentive plans (in shares)		117
Issuance of common stock under stock incentive plans	1,122		1,122
Stock repurchases (in shares)		(18)
Stock repurchases	(843)		(843)
Excess tax benefit from share-based compensation	1,421		1,421
Other	(79)		6			(85)
Ending Balances (in shares) at Jun. 30, 2016		80,863
Ending Balances at Jun. 30, 2016	$ 1,476,295	$ 81	28,696	1,385,484	(37,827)	99,861
Beginning Balances (in shares) at Dec. 31, 2016	81,231	81,231
Beginning Balances at Dec. 31, 2016	$ 1,568,725	$ 81	32,157	1,484,391	(45,406)	97,502
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (excludes $1,300 and $827 during the six months ended June 30, 2016 and $969 and $810 during the six months ended June 30, 2017 related to redeemable and mandatorily redeemable noncontrolling interests, respectively)	121,098			118,805		2,293
Other comprehensive income (excludes $168 for the six months ended June 30, 2016 and $87 for the six months ended June 30, 2017 related to mandatorily redeemable noncontrolling interests)	8,469				8,331	138
Formation of noncontrolling interests	335					335
Distributions to noncontrolling interests	(983)					(983)
Purchase of noncontrolling interests (excludes $1,185 related to redeemable noncontrolling interests) in 2017	(216)		(216)
Share-based compensation	7,993		7,993
Issuance of common stock under stock incentive plans (in shares)		42
Issuance of common stock under stock incentive plans	90		90
Stock repurchases (in shares)		(3)
Stock repurchases	(129)		(129)
Other	$ 99		1,090			(991)
Ending Balances (in shares) at Jun. 30, 2017	81,270	81,270
Ending Balances at Jun. 30, 2017	$ 1,705,481	$ 81	$ 40,985	$ 1,603,196	$ (37,075)	$ 98,294