Consolidated Statements Of Changes In Equity (USD $)	Total	Common Stock Including Additional Paid in Capital [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, 2011		$ 173,187,000	$ 443,058,000	$ 132,222,000	$ 748,467,000	$ 170,636,000
Balance (in shares) at Dec. 31, 2011		31,284,000
Issuance of restricted common stock (in shares)		255,000
Stock options exercised		2,521,000			2,521,000
Stock options exercised (in shares)		111,000
Stock repurchased	(1,560,000)	(2,823,000)			(2,823,000)
Stock repurchased (in shares)	(61,149)	(109,000)
Share-based compensation, value	1,792,000	1,792,000			1,792,000
Tax Benefit from Stock Options Exercised		198,000			198,000
Net earnings	54,939,000		14,776,000	6,062,000	20,838,000	34,101,000
Distributions to noncontrolling interests, net of capital contributions				(6,434,000)	(6,434,000)	(32,546,000)
Sale of noncontrolling interest, value		(1,587,000)		1,728,000	141,000	0
Acquisitions and other transactions impacting noncontrolling interests				2,223,000	2,223,000	2,467,000
Disposals and other transactions impacting noncontrolling interests		(369,000)			(369,000)	176,000
Balance at Mar. 31, 2012		172,919,000	457,834,000	135,801,000	766,554,000	174,834,000
Balance (in shares) at Mar. 31, 2012		31,541,000
Balance at Dec. 31, 2012	1,000,466,000	183,867,000	505,621,000	310,978,000	1,000,466,000	175,382,000
Balance (in shares) at Dec. 31, 2012		31,941,000
Issuance of restricted common stock (in shares)		263,000
Cancellation of restricted common stock (in shares)		(14,000)
Stock options exercised		5,691,000			5,691,000
Stock options exercised (in shares)	236,579	237,000
Stock repurchased	(13,943,000)	(16,758,000)			(16,758,000)
Stock repurchased (in shares)	(438,668)	(528,000)
Share-based compensation, value	2,050,000	2,050,000			2,050,000
Tax Benefit from Stock Options Exercised		1,630,000			1,630,000
Net earnings	62,273,000		17,811,000	12,232,000	30,043,000	32,230,000
Distributions to noncontrolling interests, net of capital contributions				(11,891,000)	(11,891,000)	(31,823,000)
Purchase of noncontrolling interest, value		(304,000)		(133,000)	(437,000)	(316,000)
Sale of noncontrolling interest, value		(644,000)		1,419,000	775,000	236,000
Acquisitions and other transactions impacting noncontrolling interests				266,000	266,000	0
Disposals and other transactions impacting noncontrolling interests		0		(317,000)	(317,000)	0
Balance at Mar. 31, 2013	$ 1,011,518,000	$ 175,532,000	$ 523,432,000	$ 312,554,000	$ 1,011,518,000	$ 175,709,000
Balance (in shares) at Mar. 31, 2013		31,899,000