Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Net unrealized gain (loss) on derivative designated as cash flow hedge			$ (20,400,000)		$ 8,300,000
Loss expected to be reclassified into interest expense within the next 12 months			4,100,000
Net unrealized loss (gain) on derivative financial instruments not designated as cash flow hedges	$ 0	$ (432,000)	$ 48,000	$ (1,551,000)