Commitments and Contingencies (Details)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) a	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Other Commitments [Line Items]
Area of Land | a		378
Rent expense		$ 8,644,000	$ 8,509,000	$ 8,444,000
Boulder Station Lease [Member]
Other Commitments [Line Items]
Ground lease, monthly rental payments		$ 222,933
Ground lease, intervals between options to purchase land		5 years
Boulder Station Lease [Member] | Fair Market Value [Member]
Other Commitments [Line Items]
Ground lease, period between rent adjustments		10 years
Ground lease, minimum increase to fair market value adjustment (percent)		8.00%
Boulder Station Lease [Member] | Cost of Living Factor [Member]
Other Commitments [Line Items]
Ground lease, period between rent adjustments		10 years
Texas Station Lease [Member]
Other Commitments [Line Items]
Land Subject to Ground Leases | a		47
Ground lease, monthly rental payments		$ 366,435
Ground lease, intervals between options to purchase land		5 years
Texas Station Lease [Member] | Fair Market Value [Member]
Other Commitments [Line Items]
Ground lease, period between rent adjustments		10 years
Ground lease, minimum increase to fair market value adjustment (percent)		8.00%
Texas Station Lease [Member] | Cost of Living Factor [Member]
Other Commitments [Line Items]
Ground lease, period between rent adjustments		10 years
Wild Wild West Lease [Member]
Other Commitments [Line Items]
Land Subject to Ground Leases | a		20
Ground lease, monthly rental payments		$ 128,778
After January 2020 [Member] | Wild Wild West Lease [Member]
Other Commitments [Line Items]
Ground lease, period between rent adjustments		3 years
Maximum [Member] | Boulder Station Lease [Member]
Other Commitments [Line Items]
Ground lease, term		65 years
Maximum [Member] | Texas Station Lease [Member]
Other Commitments [Line Items]
Ground lease, term		65 years
Subsequent Event [Member] | Wild Wild West Lease [Member]
Other Commitments [Line Items]
Ground lease, monthly rental payments	$ 131,998