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 [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)		281,000
Cancellation of restricted common stock (in shares)		(2,000)
Stock options exercised		11,928,000			11,928,000
Stock options exercised (in shares)		580,000
Stock repurchased	(11,838,000)	(13,101,000)			(13,101,000)
Stock repurchased (in shares)	(415,084)	(464,000)
Share-based compensation, value	5,119,000	5,119,000			5,119,000
Tax benefit related to exercise of stock options		1,318,000			1,318,000
Net earnings	164,249,000		45,749,000	18,578,000	64,327,000	99,922,000
Distributions to noncontrolling interests, net of capital contributions				(20,192,000)	(20,192,000)	(102,804,000)
Purchase of noncontrolling interest, value		166,000		(289,000)	(123,000)	(81,000)
Sale of noncontrolling interest, value		(2,277,000)		3,555,000	1,278,000	0
Acquisitions and other transactions impacting noncontrolling interests				2,212,000	2,212,000	7,038,000
Disposals and other transactions impacting noncontrolling interests		(369,000)			(369,000)	176,000
Balance at Sep. 30, 2012		175,971,000	488,807,000	136,086,000	800,864,000	174,887,000
Balance (in shares) at Sep. 30, 2012		31,679,000
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)		292,000
Cancellation of restricted common stock (in shares)		(16,000)
Stock options exercised		23,289,000			23,289,000
Stock options exercised (in shares)	960,051	961,000
Stock repurchased	(32,169,000)	(35,481,000)			(35,481,000)
Stock repurchased (in shares)	(920,851)	(1,024,000)
Share-based compensation, value	6,070,000	6,070,000			6,070,000
Tax benefit related to exercise of stock options		4,847,000			4,847,000
Net earnings	190,376,000		53,145,000	36,962,000	90,107,000	100,269,000
Distributions to noncontrolling interests, net of capital contributions				(36,301,000)	(36,301,000)	(100,504,000)
Purchase of noncontrolling interest, value		(223,000)		(316,000)	(539,000)	(316,000)
Sale of noncontrolling interest, value		(1,545,000)		2,327,000	782,000	634,000
Acquisitions and other transactions impacting noncontrolling interests				38,371,000	38,371,000	0
Disposals and other transactions impacting noncontrolling interests				(317,000)	(317,000)	(130,000)
Balance at Sep. 30, 2013	$ 1,091,294,000	$ 180,824,000	$ 558,766,000	$ 351,704,000	$ 1,091,294,000	$ 175,335,000
Balance (in shares) at Sep. 30, 2013		32,154,000