Components of Shareholders' Equity and Changes Therein (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Stockholders Equity Note [Line Items]
Beginning Balance	$ 846,309	$ 980,276
Net loss	(11,899)	(26,340)
Dividends Paid(0.05625 per share)	(2,586)	(2,576)
All other Changes	1,637	3,142
Ending balance	833,461	954,502
Common Stock
Stockholders Equity Note [Line Items]
Beginning Balance	270	267
All other Changes	1	1
Ending balance	271	268
Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Beginning Balance	690,131	680,981
All other Changes	1,614	3,009
Ending balance	691,745	683,990
Retained Earnings
Stockholders Equity Note [Line Items]
Beginning Balance	157,242	300,473
Net loss	(11,899)	(26,340)
Dividends Paid(0.05625 per share)	(2,586)	(2,576)
Ending balance	142,757	271,557
Deferred Compensation Plan
Stockholders Equity Note [Line Items]
Beginning Balance	3,620	2,743
All other Changes	40	143
Ending balance	3,660	2,886
Accumulated Other Comprehensive Income (Loss)
Stockholders Equity Note [Line Items]
Beginning Balance	(1,084)	(938)
All other Changes	23	34
Ending balance	(1,061)	(904)
Treasury Stock
Stockholders Equity Note [Line Items]
Beginning Balance	(3,870)	(3,250)
All other Changes	(41)	(45)
Ending balance	$ (3,911)	$ (3,295)