Convertible Notes, Long-Term Debt and Credit Facility - Credit Facility (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
Credit facility, financial covenant, EBITDA to debt ratio, upper range	1.10
Credit facility, financial covenant, funded debt to adjusted EBITDA ratio	4.0
Covenant, Percent of Adjusted EBITDA Which Must Be Prepaid	25.00%
Credit Facility Ceiling Value, Applicable to 25% Of Adjusted EBITDA Which Must Be Paid	$ 3,000,000
Covenant, Maximum Number of Days From Year End By Which Prepayment of 25% of Adjusted EBTDA is Due	60 days
Excess Cash Flow Minimum Achieved Under Loan Covenant		3,000,000
Amount Company Will Prepay on Term Loan Due To Covenant Requirement	3,000,000
Amount borrowed	54,973,000	62,105,000
Line of Credit [Member]
Line of Credit Facility [Line Items]
Annual limit on capital expenditures	36,000,000
Line of Credit [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	75,000,000.0
Credit facility, commitment fee percentage	0.25%
Credit facility, amount outstanding	13,900,000
Credit facility, availability	74,800,000
Credit facility, available borrowing capacity, net of outstanding borrowings	60,900,000
Letter of Credit [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Maximum borrowing capacity	10,000,000
Term loan [Member]
Line of Credit Facility [Line Items]
Debt, face amount	50,000,000.0
Amount borrowed	41,048,000	45,833,000
Monthly principal payments	600,000
PNC Bank Base Rate [Member] | Term loan [Member]
Line of Credit Facility [Line Items]
Debt, interest rate at period end	4.50%
Amount borrowed	100,000
London Interbank Lending Rate (LIBOR) [Member] | Line of Credit [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Base lending rate	3.25%
Credit facility, interest rate at period end	1.65%
London Interbank Lending Rate (LIBOR) [Member] | Term loan [Member]
Line of Credit Facility [Line Items]
Debt, interest rate at period end	2.41%
Amount borrowed	$ 41,000,000
Minimum [Member] | PNC Bank Base Rate [Member] | Line of Credit [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility, variable percentage rate spread	0.50%
Minimum [Member] | PNC Bank Base Rate [Member] | Term loan [Member]
Line of Credit Facility [Line Items]
Credit facility, variable percentage rate spread	1.25%
Minimum [Member] | London Interbank Lending Rate (LIBOR) [Member] | Line of Credit [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility, variable percentage rate spread	1.50%
Minimum [Member] | London Interbank Lending Rate (LIBOR) [Member] | Term loan [Member]
Line of Credit Facility [Line Items]
Credit facility, variable percentage rate spread	2.25%
Maximum [Member] | PNC Bank Base Rate [Member] | Line of Credit [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility, variable percentage rate spread	1.00%
Maximum [Member] | PNC Bank Base Rate [Member] | Term loan [Member]
Line of Credit Facility [Line Items]
Credit facility, variable percentage rate spread	1.75%
Maximum [Member] | London Interbank Lending Rate (LIBOR) [Member] | Line of Credit [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility, variable percentage rate spread	2.00%
Maximum [Member] | London Interbank Lending Rate (LIBOR) [Member] | Term loan [Member]
Line of Credit Facility [Line Items]
Credit facility, variable percentage rate spread	2.75%