Earnings Per Share (Details) (USD $)	3 Months Ended			6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		0 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Restricted stock	Jun. 30, 2012 Restricted stock	Jun. 30, 2013 Restricted stock	Jun. 30, 2012 Restricted stock	Jun. 30, 2013 SARs	Jun. 30, 2012 SARs	Jun. 30, 2013 SARs	Jun. 30, 2012 SARs	Jun. 30, 2013 Stock options	Jun. 30, 2012 Stock options	Jun. 30, 2013 Stock options	Jun. 30, 2012 Stock options	Jun. 30, 2013 Non employee director deferred compensation	Jun. 30, 2012 Non employee director deferred compensation	Jun. 30, 2013 Non employee director deferred compensation	Jun. 30, 2012 Non employee director deferred compensation	Jun. 30, 2013 Convertible senior note	Jun. 30, 2012 Convertible senior note	Jun. 30, 2013 Convertible senior note	Jun. 30, 2012 Convertible senior note	Nov. 15, 2010 3.25% Convertible Senior Notes due 2016 Note
Reconciliation of Weighted-Average Diluted Shares Outstanding
Weighted average common shares outstanding - basic	30,332,000		26,597,000	30,301,000	25,103,000
Incremental Common Shares Attributable to Share-based Payment Arrangements						313,000	125,000	0	157,000	26,000	3,000	0	4,000	1,000	0	0	0	4,000	3,000		4,000	338,000	0	0	0
Weighted Average Number of Shares Outstanding - Diluted	31,014,000	30,301,000	26,728,000	30,301,000	25,268,000
Anti-dilutive Effect
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	25,000		184,000	1,164,000	152,000	5,000	90,000	893,000	64,000	20,000	87,000	54,000	81,000	0	7,000	7,000	7,000	0	0	4,000	0	0	0	206,000	0
Convertible Senior Note Due 2016
Convertible Senior Note																										115,000
Convertible Senior Note Principal Amount ($ per Note)																										$ 1,000
3.25% Convertible Note, Number of Shares Convertible																										2,700,000
3.25% Convertible Note, Conversion Price																										$ 42.40