Long-term Obligations - Fan Pier Leases (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 building lease sqft	Mar. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Number of leases	2
Area of real estate property (in square feet)	1,100,000
Number of buildings under lease agreement	2
Optional term of lease agreement (in years)	10 years
Property, Plant and Equipment, Net		$ 708,616,000	$ 715,812,000
Construction financing lease obligation, current and noncurrent		473,300,000	473,400,000
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Net		$ 512,300,000	$ 515,000,000