Share-Based Compensation (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended					12 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 Restricted Stock [Member]	Dec. 31, 2012 Two Thousand Twelve Stock Option Plan [Member]	May 31, 2012 Two Thousand Twelve Stock Option Plan [Member]	Dec. 31, 2012 1997 Plan [Member]	Dec. 31, 2012 2005 Plan [Member]	May 31, 2005 2005 Plan [Member]	Dec. 31, 2012 Expected to be recognized during 2013 [Member]	Dec. 31, 2013 Expected to be recognized during 2014 [Member]
Common stock on date granted term period, years								5		5	10
Shares available for grants								1,500,000	1,500,000	0	20,635	1,500,000
Combined share-based compensation expense for 2005 Plan and 1997 Plan			$ 2,168,000	$ 3,087,000	$ 2,368,000
Expenses, stock options	2,167,000	3,077,000			2,343,000
Expenses, restricted stock	1,000	10,000			25,000
Unrecognized compensation cost	448,000						0						400,000	48,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 6.36	$ 9.91	$ 6.26
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term			3 years 8 months 15 days
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized			1,732,310
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value			2,102,000
Intrinsic Value per Share, Outstanding			$ 9.93
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value			436,000
Intrinsic Value per Share, Exercisable			$ 12.45
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Total Intrinsic Value			$ 5,527,000	$ 2,567,000	$ 3,510,000
Intrinsic Value per Share, Exercises in Period			$ 8.67	$ 12.94	$ 13.28
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				0 years 1 month 4 days 6 hours 12 minutes	0 years 6 months 14 days	1 year 0 months 9 days 11 hours 45 minutes 36 seconds		5 years			10 years