Components of Shareholders' Equity and Changes Therein (Detail) (USD $)	3 Months Ended		9 Months Ended														3 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Common stock	Sep. 30, 2011 Common stock	Sep. 30, 2012 Additional paid-in capital	Sep. 30, 2011 Additional paid-in capital	Sep. 30, 2012 Retained earnings	Sep. 30, 2011 Retained earnings	Sep. 30, 2012 Deferred compensation plan	Sep. 30, 2011 Deferred compensation plan	Sep. 30, 2012 Accumulated other comprehensive loss	Sep. 30, 2011 Accumulated other comprehensive loss	Sep. 30, 2012 Treasury stock	Sep. 30, 2011 Treasury stock	Dec. 31, 2012 Subsequent event [Member]	Oct. 31, 2012 Subsequent event [Member]
Stockholders Equity Note [Line Items]
Stock Issued During Period, Shares, New Issues																	9,200,000
Beginning Balance			$ 846,309,000	$ 980,276,000	$ 270,000	$ 267,000	$ 690,131,000	$ 680,981,000	$ 157,242,000	$ 300,473,000	$ 3,620,000	$ 2,743,000	$ (1,084,000)	$ (938,000)	$ (3,870,000)	$ (3,250,000)
Net Loss	(32,611,000)	(6,718,000)	(50,148,000)	(104,976,000)	0	0	0	0	(50,148,000)	(104,976,000)	0	0	0	0	0	0
Dividends Paid ($0.1125 per share)			(5,176,000)	(7,736,000)	0	0	0	0	(5,176,000)	(7,736,000)	0	0	0	0	0	0
All Other Changes			4,297,000	6,799,000	1,000	2,000	4,228,000	6,571,000	0	0	(548,000)	685,000	69,000	102,000	547,000	(561,000)
Ending balance	795,282,000	874,363,000	795,282,000	874,363,000	271,000	269,000	694,359,000	687,552,000	101,918,000	187,761,000	3,072,000	3,428,000	(1,015,000)	(836,000)	(3,323,000)	(3,811,000)
Proceeds from Issuance of Common Stock																	44,000,000
Depositary Shares Issued During Period, New Issues																	1,150,000
Preferred Stock, Dividend Rate, Percentage																	6.00%
Proceeds from Issuance of Convertible Preferred Stock																	$ 111,000,000
Preferred Stock, Liquidation Preference Per Share																		$ 100.00
Annual Dividend Payable, 6.00% Preferred Stock, Per Share																	$ 6.00
Conversion Rate, Convertible Preferred Stock into Common, Per Share																	16.6667
Conversion Price per Share																		$ 6.00
Premium, Conversion Price to concurrent Common Stock Offering Price																		20.00%
Common Stock Offering Price, New Issue																		$ 5.00