Fair Value Measurements (Details) (USD $) | Mar. 31, 2014 | Dec. 31, 2013 |
In Thousands, unless otherwise specified |
Prepaid Expenses and Other Current Assets [Member] | Interest rate swap [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest rate swaps, assets | $2,509 | ' |
Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member] | Interest rate swap [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest rate swaps, assets | 0 | ' |
Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 3 [Member] | Interest rate swap [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest rate swaps, assets | 0 | ' |
Fair Value, Measurements, Recurring [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Total assets at fair value | 41,241 | 41,852 |
Total liabilities at fair value | 1,946 | 1,162 |
Fair Value, Measurements, Recurring [Member] | Cash and Cash Equivalents [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 3,719 | 7,101 |
Fair Value, Measurements, Recurring [Member] | U.S. Equity Mutual Funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 20,005 | 16,479 |
Fair Value, Measurements, Recurring [Member] | Foreign equity mutual funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 4,383 | 4,323 |
Fair Value, Measurements, Recurring [Member] | Fixed income mutual funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 5,000 | 4,616 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Total assets at fair value | 33,107 | 32,519 |
Total liabilities at fair value | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 3,719 | 7,101 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Equity Mutual Funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 20,005 | 16,479 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign equity mutual funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 4,383 | 4,323 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed income mutual funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 5,000 | 4,616 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Total assets at fair value | 8,134 | 9,333 |
Total liabilities at fair value | 1,946 | 1,162 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Equity Mutual Funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign equity mutual funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed income mutual funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Total assets at fair value | 0 | 0 |
Total liabilities at fair value | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Equity Mutual Funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign equity mutual funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed income mutual funds [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Prepaid Expenses and Other Current Assets [Member] | Fair Value, Inputs, Level 1 [Member] | Interest rate swap [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest rate swaps, assets | 2,509 | ' |
Fair Value, Measurements, Recurring [Member] | Direct Financing Leases and Other Assets [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 33,107 | 32,519 |
Fair Value, Measurements, Recurring [Member] | Direct Financing Leases and Other Assets [Member] | Interest rate swap [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest rate swaps, assets | 5,625 | 9,333 |
Fair Value, Measurements, Recurring [Member] | Direct Financing Leases and Other Assets [Member] | Fair Value, Inputs, Level 1 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 33,107 | 32,519 |
Fair Value, Measurements, Recurring [Member] | Direct Financing Leases and Other Assets [Member] | Fair Value, Inputs, Level 1 [Member] | Interest rate swap [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest rate swaps, assets | ' | 0 |
Fair Value, Measurements, Recurring [Member] | Direct Financing Leases and Other Assets [Member] | Fair Value, Inputs, Level 2 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Direct Financing Leases and Other Assets [Member] | Fair Value, Inputs, Level 2 [Member] | Interest rate swap [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest rate swaps, assets | 5,625 | 9,333 |
Fair Value, Measurements, Recurring [Member] | Direct Financing Leases and Other Assets [Member] | Fair Value, Inputs, Level 3 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Investments held in Rabbi Trusts | 0 | 0 |
Fair Value, Measurements, Recurring [Member] | Direct Financing Leases and Other Assets [Member] | Fair Value, Inputs, Level 3 [Member] | Interest rate swap [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest rate swaps, assets | ' | 0 |
Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member] | Fair Value, Inputs, Level 1 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest Rate Derivative Liabilities, at Fair Value | 0 | ' |
Fair Value, Measurements, Recurring [Member] | Accrued Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest Rate Derivative Liabilities, at Fair Value | 0 | ' |
Fair Value, Measurements, Recurring [Member] | Other noncurrent liabilities [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest Rate Derivative Liabilities, at Fair Value | 1,946 | 1,162 |
Fair Value, Measurements, Recurring [Member] | Other noncurrent liabilities [Member] | Fair Value, Inputs, Level 1 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest Rate Derivative Liabilities, at Fair Value | ' | 0 |
Fair Value, Measurements, Recurring [Member] | Other noncurrent liabilities [Member] | Fair Value, Inputs, Level 2 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest Rate Derivative Liabilities, at Fair Value | 1,946 | 1,162 |
Fair Value, Measurements, Recurring [Member] | Other noncurrent liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | ' | ' |
Assets and liabilities measured at fair value on a recurring basis | ' | ' |
Interest Rate Derivative Liabilities, at Fair Value | ' | $0 |