Stock-Based Compensation Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified		3 Months Ended		12 Months Ended						3 Months Ended
	May 24, 2007 The 2007 plan	Mar. 31, 2014 The 2007 plan Restricted stock	Mar. 31, 2013 The 2007 plan Restricted stock	Dec. 31, 2013 The 2007 plan Restricted stock	Dec. 31, 2012 The 2007 plan Restricted stock	Dec. 31, 2013 The 2007 plan Restricted stock vesting over 4 years	Dec. 31, 2012 The 2007 plan Restricted stock vesting over 4 years	Dec. 31, 2013 The 2007 plan Restricted stock vesting on the first anniversary date from date of issuance	Dec. 31, 2012 The 2007 plan Restricted stock vesting on the first anniversary date from date of issuance	Mar. 31, 2014 1996 Plan	Mar. 31, 2013 1996 Plan
Stock-based compensation plans
Number of shares authorized	2,000,000
Number of shares awarded		1,784,946
Number Outstanding
Balance at the beginning of the period (in shares)		515,130	682,654	682,654	651,294
Shares granted		35,000				130,000	283,000	21,408	28,040
Shares cancelled				(60,110)	(8,988)
Shares vested		(39,000)		(258,822)	(270,692)
Balance at the end of the period (in shares)		511,130		515,130	682,654
Stock compensation expense (in dollars)		$ 0.8	$ 0.8
Remaining average vesting period for recognition of unrecognized compensation expense		1 year 10 months 24 days	2 years 3 months 18 days
Unrecognized compensation expense (in dollars)		5.0	5.8
Intrinsic value of unvested awards (in dollars)		10.5	9.7
Stock options exercised (in shares)										21,842	12,375
Options cancelled (in shares)											65,000
Stock options outstanding (in shares)										53,595
Intrinsic value of outstanding stock options (in dollars)										$ 0.6