Consolidated Statements Of Changes In Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Mandatory Convertible Preferred Stock [Member]	Retained Earnings [Member]	Non-Controlling Interests - Non-Redeemable [Member]	Total Equity (Permanent) [Member]	Non-controlling Interests - Redeemable (Temporary Equity) [Member]
Balance at Dec. 31, 2014		$ 885,393	$ 166,632	$ 627,522	$ 418,684	$ 2,098,231	$ 184,099
Balance (in shares) at Dec. 31, 2014		48,113,000	1,725,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 68,755			21,038	15,037	36,075	32,680
Issuance of restricted common stock (in shares)		296,000
Cancellation of restricted common stock (in shares)		(6,000)
Stock options exercised		$ 1,746				1,746
Stock options exercised (in shares)		77,000
Stock repurchased	$ (3,700)	$ (3,684)				(3,684)
Stock repurchased (in shares)	(67,000)	(67,000)
Share-based compensation		$ 3,709				3,709
Tax benefit related to exercise of share-based awards		3,317				3,317
Dividends paid on preferred stock				(2,264)		(2,264)
Acquisitions and other transactions impacting noncontrolling interests		144			23,012	23,156	(646)
Distributions to noncontrolling interests, net of capital contributions					(14,564)	(14,564)	(32,544)
Disposals and other transactions impacting noncontrolling interests		(1,877)			2,951	1,074	(130)
Balance at Mar. 31, 2015		$ 888,748	$ 166,632	646,296	445,120	2,146,796	183,459
Balance (in shares) at Mar. 31, 2015		48,413,000	1,725,000
Balance at Dec. 31, 2015	$ 2,764,747	$ 1,345,418	$ 166,632	781,413	471,284	2,764,747	175,732
Balance (in shares) at Dec. 31, 2015		54,294,000	1,725,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	$ 84,704			30,863	17,477	48,340	36,364
Issuance of restricted common stock (in shares)		567,000
Cancellation of restricted common stock (in shares)		(7,000)
Stock options exercised		$ 276				276
Stock options exercised (in shares)	12,667	13,000
Stock repurchased	$ (5,700)	$ (5,688)				(5,688)
Stock repurchased (in shares)	(77,780)	(78,000)
Share-based compensation		$ 7,168				7,168
Tax benefit related to exercise of share-based awards		3,605				3,605
Dividends paid on preferred stock				(2,264)		(2,264)
Acquisitions and other transactions impacting noncontrolling interests		542			(1,233)	(691)	(4)
Distributions to noncontrolling interests, net of capital contributions					(18,688)	(18,688)	(37,866)
Disposals and other transactions impacting noncontrolling interests		(1,444)			1,471	27	445
Balance at Mar. 31, 2016	$ 2,796,832	$ 1,349,877	$ 166,632	$ 810,012	$ 470,311	$ 2,796,832	$ 174,671
Balance (in shares) at Mar. 31, 2016		54,789,000	1,725,000