Commitments and Contingencies (Details)			1 Months Ended		12 Months Ended
	Oct. 06, 2017 USD ($)	Sep. 16, 2015 USD ($)	May 31, 2014 USD ($)	Jun. 30, 2013 USD ($)	Dec. 31, 2017 USD ($) executive_officer	Jan. 31, 2018 USD ($)	Dec. 31, 2016
Loss Contingencies [Line Items]
Number of executive officers entitled to severance benefits | executive_officer					4
Subsequent Event [Member]
Loss Contingencies [Line Items]
Maximum retirement agreement amount						$ 795,000
Senior Notes [Member] | Senior Notes Due 2024 [Member]
Loss Contingencies [Line Items]
Debt interest rate percentage			4.40%		4.40%		4.40%
Redemption price, percentage			99.883%
Senior Notes [Member] | Senior Notes Due 2023 [Member]
Loss Contingencies [Line Items]
Debt interest rate percentage				4.25%	4.25%		4.25%
Redemption price, percentage				99.026%
LCIF [Member] | Senior Notes [Member] | Senior Notes Due 2024 [Member] | Financial Guarantee [Member]
Loss Contingencies [Line Items]
Maximum guarantee exposure			$ 250,000,000
LCIF [Member] | Senior Notes [Member] | Senior Notes Due 2023 [Member] | Financial Guarantee [Member]
Loss Contingencies [Line Items]
Maximum guarantee exposure				$ 250,000,000
Maximum [Member] | LCIF [Member]
Loss Contingencies [Line Items]
Debt interest rate percentage					6.50%		6.50%
Bridgewater Hills Corporate Center, LLC [Member]
Loss Contingencies [Line Items]
Damages sought		$ 9,200,000
Amount awarded to other party	$ 2,050,000
Legal fees					$ 2,255,000
Bridgewater Hills Corporate Center, LLC [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Estimate of possible loss		$ 10,000,000