Fair Value Measurements (Financial Assets and Liabilities Measured at Fair Value) (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Net Asset (Liability) [Abstract]
Total assets	$ 23,166	$ 35,162
Marketable securities
Fair Value, Net Asset (Liability) [Abstract]
Total assets	23,166	35,156
Interest rate cap (included in other assets)
Fair Value, Net Asset (Liability) [Abstract]
Total assets	0	6
Level 1
Fair Value, Net Asset (Liability) [Abstract]
Total assets	23,166	35,156
Level 1 | Marketable securities
Fair Value, Net Asset (Liability) [Abstract]
Total assets	23,166	35,156
Level 1 | Interest rate cap (included in other assets)
Fair Value, Net Asset (Liability) [Abstract]
Total assets	0	0
Level 2
Fair Value, Net Asset (Liability) [Abstract]
Total assets	0	6
Level 2 | Marketable securities
Fair Value, Net Asset (Liability) [Abstract]
Total assets	0	0
Level 2 | Interest rate cap (included in other assets)
Fair Value, Net Asset (Liability) [Abstract]
Total assets	0	6
Level 3
Fair Value, Net Asset (Liability) [Abstract]
Total assets	0	0
Level 3 | Marketable securities
Fair Value, Net Asset (Liability) [Abstract]
Total assets	0	0
Level 3 | Interest rate cap (included in other assets)
Fair Value, Net Asset (Liability) [Abstract]
Total assets	$ 0	$ 0