Changes in Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Increase (Decrease) in Equity
Balances	$ 2,495,855
Proceeds from the exercise of stock options, including related tax effect	3,538
Dividends declared	(25,665)
Equity based compensation and issuance of restricted stock	5,020
Contributions from noncontrolling investors	89
Distributions to noncontrolling investors	(39)
Net income (loss)	33,698	41,252
Balances	2,512,496
Common Stock
Increase (Decrease) in Equity
Balances	645
Proceeds from the exercise of stock options, including related tax effect	1
Balances	646
Additional Paid-In Capital
Increase (Decrease) in Equity
Balances	1,085,694
Proceeds from the exercise of stock options, including related tax effect	3,537
Equity based compensation and issuance of restricted stock	3,050
Balances	1,092,281
Retained Earnings
Increase (Decrease) in Equity
Balances	2,179,513
Dividends declared	(25,665)
Equity based compensation and issuance of restricted stock	(14)
Net income (loss)	38,579
Balances	2,192,413
Treasury Stock
Increase (Decrease) in Equity
Balances	(718,529)
Equity based compensation and issuance of restricted stock	1,984
Balances	(716,545)
Noncontrolling Interests
Increase (Decrease) in Equity
Balances	(51,468)
Contributions from noncontrolling investors	89
Distributions to noncontrolling investors	(39)
Net income (loss)	(4,881)
Balances	(56,299)
Redeemable Noncontrolling Interests
Increase (Decrease) in Equity
Balances	116,514
Contributions from noncontrolling investors	5,320
Balances	$ 121,834