Long-term Debt - Narrative (Details) (USD $)	3 Months Ended			0 Months Ended	3 Months Ended			5 Months Ended	3 Months Ended	5 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	May 30, 2013 Revolving Credit Facility [Member]	Mar. 31, 2014 Revolving Credit Facility [Member]	Mar. 31, 2013 Revolving Credit Facility [Member]	Mar. 31, 2014 Line of Credit [Member] Revolving Credit Facility [Member] Minimum [Member]	May 30, 2013 Line of Credit [Member] Revolving Credit Facility [Member] Minimum [Member]	Mar. 31, 2014 Line of Credit [Member] Revolving Credit Facility [Member] Maximum [Member]	May 30, 2013 Line of Credit [Member] Revolving Credit Facility [Member] Maximum [Member]
Debt Instrument [Line Items]
Revolving credit facility, maximum borrowing capacity					$ 200,000,000
Revolving credit facility, potentially additional borrowing capacity					100,000,000
Revolving credit facility, margin added to variable interest rate							1.25%	1.75%	1.75%	2.25%
Revolving credit facility, permitted aggregate stock repurchases				50,000,000
Revolving credit facility, Maximum permitted stock repurchases in any year				15,000,000
Revolving credit facility, ceiling for dividends				75,000,000
Revolving credit facility, amendment fees				300,000
Revolving credit facility, average borrowings					13,600,000	34,300,000
Minimum amount borrowed at any one time outstanding					0	15,000,000
Maximum amount borrowed at any one time outstanding					46,300,000	73,300,000
Revolving credit facility, weighted-average interest rate					1.60%	2.00%
Total unused facility fees and letter of credit participation fees					200,000	200,000
Amortization of debt issuance costs	100,000	100,000
Unamortized debt issuance costs	$ 1,400,000		$ 1,400,000