Consolidated Statements Of Changes In Equity (USD $) In Thousands, except Share data, unless otherwise specified	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, 2013		$ 185,873		$ 578,324	$ 361,359	$ 1,125,556	$ 177,697
Balance (in shares) at Dec. 31, 2013		32,353,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	60,114			17,195	12,219	29,414	30,700
Issuance of restricted common stock (in shares)		200,000
Stock options exercised		488				488
Stock options exercised (in shares)		20,000
Stock repurchased		(2,857)				(2,857)
Stock repurchased (in shares)		(68,000)
Share-based compensation		2,458				2,458
Tax benefit related to exercise of stock options		1,727				1,727
Acquisitions and other transactions impacting noncontrolling interests		286			3,690	3,976	0
Distributions to noncontrolling interests, net of capital contributions					(12,753)	(12,753)	(30,441)
Disposals and other transactions impacting noncontrolling interests		(1,081)			(1,291)	(2,372)	(273)
Balance at Mar. 31, 2014		186,894	0	595,519	363,224	1,145,637	177,683
Balance (in shares) at Mar. 31, 2014		32,505,000	0
Balance at Dec. 31, 2014	2,098,231	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)	76,962	77,000
Stock repurchased		(3,684)				(3,684)
Stock repurchased (in shares)		(67,000)
Share-based compensation		3,709				3,709
Tax benefit related to exercise of stock options		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	$ 2,146,796	$ 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