Bank and Other Notes Payable - Narrative (Details) - USD ($)					12 Months Ended
	Jul. 06, 2016	Oct. 23, 2015	Mar. 29, 2013	Dec. 08, 2011	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Bank and other notes payable
Deferred finance cost					$ (12,716,000)	$ (16,025,000)
Loss on extinguishment of debt					(13,737,000)	(16,066,000)	$ 526,000
Line of Credit
Bank and other notes payable
Line of credit					1,500,000,000
Amended line of credit	$ 1,500,000,000
Extension option term	1 year
Maximum contingent borrowing capacity	$ 2,000,000,000
Line of credit					885,000,000	650,000,000
Deferred finance cost					$ (10,039,000)	$ (6,967,000)
Average interest rate (as a percent)					2.40%	1.95%
Line of Credit | Level 2
Bank and other notes payable
Fair value of line of credit					$ 865,921,000	$ 640,260,000
Line of Credit | LIBOR
Bank and other notes payable
Variable interest rate spread (as a percent)					1.45%
Line of Credit | LIBOR | Low end of range
Bank and other notes payable
Variable interest rate spread (as a percent)	1.30%				1.38%
Line of Credit | LIBOR | High end of range
Bank and other notes payable
Variable interest rate spread (as a percent)	1.90%				2.00%
Term Loan
Bank and other notes payable
Debt issued				$ 125,000,000
Loss on extinguishment of debt		$ 578,000
Term Loan | LIBOR | Low end of range
Bank and other notes payable
Variable interest rate spread (as a percent)				1.95%
Term Loan | LIBOR | High end of range
Bank and other notes payable
Variable interest rate spread (as a percent)				3.20%
Prasada Note
Bank and other notes payable
Debt issued			$ 13,330,000
Interest rate on debt (as a percent)			5.25%
Carrying value of term loan					$ 5,521,000	9,130,000
Estimated fair value of term loan					$ 5,786,000	$ 9,168,000