Components of Shareholders' Equity and Changes Therein (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Stockholders Equity Note [Line Items]
Beginning Balance			$ 846,309	$ 980,276
Net Loss	(5,638)	(71,918)	(17,537)	(98,258)
Dividends Paid ($0.1125 per share)			(5,176)	(5,156)
All Other Changes			2,992	4,745
Ending balance	826,588	881,607	826,588	881,607
Common stock
Stockholders Equity Note [Line Items]
Beginning Balance			270	267
Net Loss			0	0
Dividends Paid ($0.1125 per share)			0	0
All Other Changes			1	2
Ending balance	271	269	271	269
Additional paid-in capital
Stockholders Equity Note [Line Items]
Beginning Balance			690,131	680,981
Net Loss			0	0
Dividends Paid ($0.1125 per share)			0	0
All Other Changes			2,947	4,578
Ending balance	693,078	685,559	693,078	685,559
Retained earnings
Stockholders Equity Note [Line Items]
Beginning Balance			157,242	300,473
Net Loss			(17,537)	(98,258)
Dividends Paid ($0.1125 per share)			(5,176)	(5,156)
All Other Changes			0	0
Ending balance	134,529	197,059	134,529	197,059
Deferred compensation plan
Stockholders Equity Note [Line Items]
Beginning Balance			3,620	2,743
Net Loss			0	0
Dividends Paid ($0.1125 per share)			0	0
All Other Changes			(588)	492
Ending balance	3,032	3,235	3,032	3,235
Accumulated other comprehensive loss
Stockholders Equity Note [Line Items]
Beginning Balance			(1,084)	(938)
Net Loss			0	0
Dividends Paid ($0.1125 per share)			0	0
All Other Changes			46	68
Ending balance	(1,038)	(870)	(1,038)	(870)
Treasury stock
Stockholders Equity Note [Line Items]
Beginning Balance			(3,870)	(3,250)
Net Loss			0	0
Dividends Paid ($0.1125 per share)			0	0
All Other Changes			586	(395)
Ending balance	$ (3,284)	$ (3,645)	$ (3,284)	$ (3,645)