Condensed Consolidated Statement Of Changes In Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Shares Held In Treasury [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Non-Controlling Interests In Subsidiaries [Member]	Windcat Acquisition [Member]	Windcat Acquisition [Member] Common Stock [Member]	Windcat Acquisition [Member] Additional Paid-In Capital [Member]	Windcat Acquisition [Member] Retained Earnings [Member]	Windcat Acquisition [Member] Shares Held In Treasury [Member]	Windcat Acquisition [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Windcat Acquisition [Member] Non-Controlling Interests In Subsidiaries [Member]
Balance at Dec. 31, 2011	$ 1,808,063	$ 364	$ 1,256,209	$ 1,512,679	$ (971,687)	$ (7,958)	$ 18,456
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee Stock Purchase Plan	2,963	0	0	0	2,963	0	0
Exercise of stock options	5,051	1	5,050	0	0	0	0
Director stock awards	271	0	271	0	0	0	0
Restricted stock and restricted stock units	353	1	384	0	(32)	0	0
Stock Issued During Period, Value, Acquisitions								585	0	585	0	0	0	0
Stock Repurchased During Period, Value	(28,726)	0	0	0	(28,726)	0	0
Amortization of share awards	15,193	0	15,193	0	0	0	0
Stock Issued During Period, Value, Restricted Stock Award, Forfeitures	0	0	59	0	(59)	0	0
Acquisition of subsidiary with noncontrolling interests	13,710	0	0	0	0	0	13,710
Issuance of noncontrolling interests	83	0	0	0	0	0	83
Dividends paid to noncontrolling interests	(1,978)	0	0	0	0	0	(1,978)
Comprehensive income:
Net income	63,176	0	0	63,839	0	0	(663)
Other comprehensive income	4,740	0	0	0	0	4,354	386
Balance at Sep. 30, 2012	$ 1,883,484	$ 366	$ 1,277,751	$ 1,576,518	$ (997,541)	$ (3,604)	$ 29,994