Consolidated Statements Of Changes In Equity (USD $) In Thousands, except Share data, unless otherwise specified	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, 2012		$ 183,867	$ 505,621	$ 310,978	$ 1,000,466	$ 175,382
Balance (in shares) at Dec. 31, 2012		31,941,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted common stock (in shares)		292,000
Cancellation of restricted common stock (in shares)		(17,000)
Stock options exercised		13,728			13,728
Stock options exercised (in shares)		568,000
Stock repurchased		(26,164)			(26,164)
Stock repurchased (in shares)		(789,000)
Share-based compensation, value	(3,966)	3,966			3,966
Tax benefit related to exercise of stock options		2,968			2,968
Net earnings and comprehensive income	128,109		36,374	25,450	61,824	66,285
Distributions to noncontrolling interests, net of capital contributions				(24,371)	(24,371)	(66,879)
Purchase of noncontrolling interest, value		(223)		(316)	(539)	(316)
Sale of noncontrolling interest, value		(1,471)		2,222	751	628
Acquisitions and other transactions impacting noncontrolling interests				11,153	11,153	0
Disposals and other transactions impacting noncontrolling interests		0		(317)	(317)
Balance at Jun. 30, 2013		176,671	541,995	324,799	1,043,465	175,100
Balance (in shares) at Jun. 30, 2013		31,995,000
Balance at Dec. 31, 2013	1,125,556	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]
Issuance of restricted common stock (in shares)		225,000
Cancellation of restricted common stock (in shares)		(7,000)
Stock options exercised		1,646			1,646
Stock options exercised (in shares)	68,868	69,000
Stock repurchased		(2,857)			(2,857)
Stock repurchased (in shares)		(68,000)
Share-based compensation, value	(4,964)	4,964			4,964
Tax benefit related to exercise of stock options		2,090			2,090
Net earnings and comprehensive income	128,286		36,156	26,788	62,944	65,342
Distributions to noncontrolling interests, net of capital contributions				(26,846)	(26,846)	(65,134)
Purchase of noncontrolling interest, value		305		(1,820)	(1,515)	0
Sale of noncontrolling interest, value		(2,199)		3,186	987	0
Acquisitions and other transactions impacting noncontrolling interests				21,255	21,255
Disposals and other transactions impacting noncontrolling interests				(5,129)	(5,129)	(842)
Balance at Jun. 30, 2014	$ 1,183,095	$ 189,822	$ 614,480	$ 378,793	$ 1,183,095	$ 177,063
Balance (in shares) at Jun. 30, 2014		32,572,000