Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Earnings Per Share Reconciliation [Abstract]
Earnings from continuing operations	$ 12,211	$ 11,556	$ 11,219	$ 6,662	$ 13,530	$ (4,826)	$ 12,280	$ 2,881	$ 41,648	$ 23,865	$ 39,904
Weighted-average shares outstanding for basic earnings per share (in shares)	63,525,000	63,456,000	63,431,000	63,431,000	63,336,000	63,334,000	63,333,000	63,131,000	63,461,000	63,284,000	62,807,000
Common equivalent shares:
Effect of stock-based compensation awards (in shares)									959,000	801,000	1,202,000
Weighted-average shares outstanding assuming dilution (in shares)	64,244,000	64,667,000	64,393,000	64,374,000	64,109,000	63,334,000	64,172,000	63,936,000	64,420,000	64,085,000	64,009,000
Basic earnings per share from continuing operations (in dollars per share)	$ 0.19	$ 0.18	$ 0.18	$ 0.11	$ 0.21	$ (0.08)	$ 0.19	$ 0.04	$ 0.66	$ 0.38	$ 0.64
Diluted earnings per share from continuing operations (in dollars per share)	$ 0.19	$ 0.18	$ 0.17	$ 0.10	$ 0.21	$ (0.08)	$ 0.19	$ 0.04	$ 0.65	$ 0.37	$ 0.62
Restricted stock (in shares)									370,400	584,700	564,100
Anti-dilutive securities excluded from computation of earnings per share (in shares)									229,000	176,000	9,000