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, 2012		$ 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)		237,000
Stock repurchased		(16,758,000)			(16,758,000)
Stock repurchased (in shares)		(528,000)
Share-based compensation, value	2,050,000	2,050,000			2,050,000
Tax benefit related to exercise of stock options		1,630,000			1,630,000
Net earnings and comprehensive income	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)
Balance at Mar. 31, 2013		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
Balance at Dec. 31, 2013	1,125,556,000	185,873,000	578,324,000	361,359,000	1,125,556,000	177,697,000
Balance (in shares) at Dec. 31, 2013		32,353,000
Issuance of restricted common stock (in shares)		200,000
Stock options exercised		488,000			488,000
Stock options exercised (in shares)	19,921	20,000
Stock repurchased		(2,857,000)			(2,857,000)
Stock repurchased (in shares)		(68,000)
Share-based compensation, value	2,458,000	2,458,000			2,458,000
Tax benefit related to exercise of stock options		1,727,000			1,727,000
Net earnings and comprehensive income	60,114,000		17,195,000	12,219,000	29,414,000	30,700,000
Distributions to noncontrolling interests, net of capital contributions				(12,753,000)	(12,753,000)	(30,441,000)
Purchase of noncontrolling interest, value		286,000		(286,000)	0	0
Sale of noncontrolling interest, value		(1,081,000)		1,665,000	584,000	0
Acquisitions and other transactions impacting noncontrolling interests				3,976,000	3,976,000
Disposals and other transactions impacting noncontrolling interests				(2,956,000)	(2,956,000)	(273,000)
Balance at Mar. 31, 2014	$ 1,145,637,000	$ 186,894,000	$ 595,519,000	$ 363,224,000	$ 1,145,637,000	$ 177,683,000
Balance (in shares) at Mar. 31, 2014		32,505,000