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	$ 257,781			97,374	49,895	147,269	110,512
Issuance of restricted common stock (in shares)		314,000
Cancellation of restricted common stock (in shares)		(7,000)
Stock options exercised		$ 2,356				2,356
Stock options exercised (in shares)		102,000
Stock repurchased	$ (3,700)	$ (3,684)				(3,684)
Stock repurchased (in shares)	(67,000)	(67,000)
Share-based compensation		$ 11,319				11,319
Tax benefit related to exercise of share-based awards		3,779				3,779
Dividends paid on preferred stock				(6,792)		(6,792)
Acquisitions and other transactions impacting noncontrolling interests		328			71,814	72,142	(645)
Distributions to noncontrolling interests, net of capital contributions					(49,345)	(49,345)	(108,574)
Disposals and other transactions impacting noncontrolling interests		(2,484)			(23,574)	(26,058)	(131)
Balance at Sep. 30, 2015		$ 897,007	$ 166,632	718,104	467,474	2,249,217	185,261
Balance (in shares) at Sep. 30, 2015		48,455,000	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	$ 283,403			116,886	54,176	171,062	112,341
Issuance of restricted common stock (in shares)		587,000
Cancellation of restricted common stock (in shares)		(13,000)
Stock options exercised		$ 450				450
Stock options exercised (in shares)	19,718	20,000
Stock repurchased	$ (6,100)	$ (6,145)				(6,145)
Stock repurchased (in shares)	(83,587)	(84,000)
Share-based compensation		$ 21,243				21,243
Tax benefit related to exercise of share-based awards		3,910				3,910
Dividends paid on preferred stock				(6,792)		(6,792)
Acquisitions and other transactions impacting noncontrolling interests		1,014			67,365	68,379	4,010
Distributions to noncontrolling interests, net of capital contributions					(56,379)	(56,379)	(114,619)
Disposals and other transactions impacting noncontrolling interests		(4,309)			(2,111)	(6,420)	413
Balance at Sep. 30, 2016	$ 2,954,055	$ 1,361,581	$ 166,632	$ 891,507	$ 534,335	$ 2,954,055	$ 177,877
Balance (in shares) at Sep. 30, 2016		54,804,000	1,725,000