Financing Arrangements (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 sqft	Dec. 31, 2013
Financing Obligations [Line Items]
Financing obligations	$ 23,519,000	$ 26,664,000
Rentable square feet of commercial real estate (in square feet)	31,157,000
Percentage of equity interest in joint venture	50.00%
Harborview Financing Obligation [Member]
Financing Obligations [Line Items]
Financing obligations	14,557,000	16,242,000
Rentable square feet of commercial real estate (in square feet)	205,000
Percentage of equity interest in joint venture	20.00%
Equity interest in consolidated affiliate	80.00%
Commencement date of put option term	Sep. 11, 2015
Transaction cost percentage to sell financing obligation	3.00%
Initial financing obligation	12,700,000
Additional financing obligation	1,800,000
Gross financing obligation increased for net income (in hundredths)	80.00%
Put option fair value	11,500,000	12,800,000
Tax Increment Financing Obligation Bond [Member]
Financing Obligations [Line Items]
Financing obligations	$ 8,962,000	$ 10,422,000
Term of period for financing obligation payments	20 years
Expiration date for financing obligation	Oct. 31, 2019
Discount rate of financing obligation	6.93%
Acquisition date of financing obligation	Dec. 01, 2007