Long-term Debt - Corporate Office Lease (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) option
Debt Instrument [Line Items]
Sale Leaseback Transaction, Net Book Value	$ 33,900
Lease term	20 years
Number of options to extend lease | option	4
Term of lease extension	5 years
Number of options to repurchase office building	2
Sale leaseback, annual rental payments	$ 3,300
Sale Leaseback, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2015	3,303
2016	3,345
2017	3,387
2018	3,429
2019	$ 3,472
Option to Purchase at End of Year Five of Original Lease [Member]
Debt Instrument [Line Items]
Number of options to repurchase office building	1
Period elapsed on original lease, until option to repurchase building	5 years
Option to Purchase at End of Year Ten of Original Lease [Member]
Debt Instrument [Line Items]
Period elapsed on original lease, until option to repurchase building	10 years
Corporate Office Lease [Member]
Debt Instrument [Line Items]
Annual increase to lease payments (percent)	1.25%
Corporate Office Lease [Member] | Maximum [Member]
Debt Instrument [Line Items]
Annual increase to lease payments (percent)	2.00%