(Schedule of Ratio of Net Indebtedness) (Details)	6 Months Ended
(Schedule of Ratio of Net Indebtedness) (Details)	Jun. 30, 2013
Line Of Credit Facility Leverage Range [Line Items]
Percent of unused portion line of credit facility trigerring lower commitment fee (as a percent)	50.00%
Less than 4.00 to 1.00 [Member]
Summary of leverage and applicable margin
Line of credit facility applicable margin rate	1.75%
Line Of Credit Facility Leverage Rate Description	Less than 4.00 to 1.00
Greater than or equal to 4.00 to 1.00 but less than 5.00 to 1.00 [Member]
Summary of leverage and applicable margin
Line of credit facility applicable margin rate	1.90%
Line Of Credit Facility Leverage Rate Description	Greater than or equal to 4.00 to 1.00 but less than 5.00 to 1.00
Greater than or equal to 5.00 to 1.00 but less than 5.50 to 1.00 [Member]
Summary of leverage and applicable margin
Line of credit facility applicable margin rate	2.10%
Line Of Credit Facility Leverage Rate Description	Greater than or equal to 5.00 to 1.00 but less than 5.50 to 1.00
Greater than or equal to 5.50 to 1.00 but less than 6.00 to 1.00 [Member]
Summary of leverage and applicable margin
Line of credit facility applicable margin rate	2.20%
Line Of Credit Facility Leverage Rate Description	Greater than or equal to 5.50 to 1.00 but less than 6.00 to 1.00
Greater than or equal to 6.00 to 1.00 [Member]
Summary of leverage and applicable margin
Line of credit facility applicable margin rate	2.50%
Line Of Credit Facility Leverage Rate Description	Greater than or equal to 6.00 to 1.00 but less than 6.50 to 1.00
Greater than or equal to 6.50 to 1.00 [Member]
Summary of leverage and applicable margin
Line of credit facility applicable margin rate	2.75%
Line Of Credit Facility Leverage Rate Description	Greater than or equal to 6.50 to 1.00
Minimum [Member]
Line Of Credit Facility Leverage Range [Line Items]
Line of credit facility, unused capacity, commitment fee (as a percent)	0.35%
Minimum [Member] \| Greater than or equal to 4.00 to 1.00 but less than 5.00 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	4.00
Minimum [Member] \| Greater than or equal to 5.00 to 1.00 but less than 5.50 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	5.00
Minimum [Member] \| Greater than or equal to 5.50 to 1.00 but less than 6.00 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	5.50
Minimum [Member] \| Greater than or equal to 6.00 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	6.00
Minimum [Member] \| Greater than or equal to 6.50 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	6.50
Maximum [Member]
Line Of Credit Facility Leverage Range [Line Items]
Line of credit facility, unused capacity, commitment fee (as a percent)	0.25%
Maximum [Member] \| Less than 4.00 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	4.00
Maximum [Member] \| Greater than or equal to 4.00 to 1.00 but less than 5.00 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	5.00
Maximum [Member] \| Greater than or equal to 5.00 to 1.00 but less than 5.50 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	5.50
Maximum [Member] \| Greater than or equal to 5.50 to 1.00 but less than 6.00 to 1.00 [Member]
Summary of leverage and applicable margin
Ratio of net indebtedness to EBITDA (as a percent)	6.00