Derivative Instruments and Hedging Activities - Derivative Instruments in Statement of Financial Position Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Asset Derivatives
Assets	$ 0	$ 0
Liability Derivatives
Liabilities	(5,700)
Total derivatives	(5,700)	(1,189)
Designated as Hedging Instrument [Member]
Asset Derivatives
Assets	0	0
Liability Derivatives
Total derivatives	(5,700)	(1,189)
Interest Rate Cap [Member] | Designated as Hedging Instrument [Member]
Asset Derivatives
Assets	0	0
Current Assets [Member]
Asset Derivatives
Assets	0
Current Liabilities [Member]
Liability Derivatives
Liabilities	(5,700)
Other Current Liabilities [Member] | Designated as Hedging Instrument [Member]
Liability Derivatives
Liabilities	(5,763)	(4,002)
Other Noncurrent Liabilities [Member] | Designated as Hedging Instrument [Member]
Liability Derivatives
Liabilities	(138)	0
Other Assets [Member] | Designated as Hedging Instrument [Member]
Liability Derivatives
Liabilities	201	2,813
Level 1 [Member]
Asset Derivatives
Assets	0
Liability Derivatives
Liabilities	0
Level 1 [Member] | Current Assets [Member]
Asset Derivatives
Assets	0
Level 1 [Member] | Current Liabilities [Member]
Liability Derivatives
Liabilities	0
Level 2 [Member]
Asset Derivatives
Assets	0
Liability Derivatives
Liabilities	(5,700)
Level 2 [Member] | Current Assets [Member]
Asset Derivatives
Assets	0
Level 2 [Member] | Current Liabilities [Member]
Liability Derivatives
Liabilities	(5,700)
Level 3 [Member]
Asset Derivatives
Assets	0
Liability Derivatives
Liabilities	0
Level 3 [Member] | Current Assets [Member]
Asset Derivatives
Assets	0
Level 3 [Member] | Current Liabilities [Member]
Liability Derivatives
Liabilities	$ 0