Notes Payable and Secured Credit Facility (Narrative) (Details)
$ in Thousands |
3 Months Ended |
12 Months Ended |
|
|
Mar. 31, 2019
USD ($)
interest_rate_swap_agreement
|
Mar. 31, 2018
USD ($)
|
Dec. 31, 2018
USD ($)
|
Dec. 31, 2017
USD ($)
|
Dec. 31, 2016
USD ($)
|
Apr. 01, 2019
USD ($)
|
| Debt Instrument [Line Items] |
|
|
|
|
|
|
| Secured credit facility, draws |
$ 10,000
|
$ 30,000
|
$ 155,000
|
$ 240,000
|
$ 240,000
|
|
| Number of interest rate swap agreements entered into during period | interest_rate_swap_agreement |
2
|
|
|
|
|
|
| Interest rate swaps, effective date |
Apr. 01, 2019
|
|
|
|
|
|
| Secured credit facility, principal amount outstanding |
$ 365,000
|
|
355,000
|
220,000
|
|
|
| Variable Rate, Subject To Interest Rate Swap [Member] |
|
|
|
|
|
|
| Debt Instrument [Line Items] |
|
|
|
|
|
|
| Secured credit facility, principal amount outstanding |
100,000
|
|
100,000
|
100,000
|
|
|
| Term Loan [Member] | Variable Rate, Subject To Interest Rate Swap [Member] |
|
|
|
|
|
|
| Debt Instrument [Line Items] |
|
|
|
|
|
|
| Secured credit facility, principal amount outstanding |
$ 100,000
|
|
$ 100,000
|
$ 100,000
|
|
|
| Term Loan [Member] | Variable Rate, Subject To Interest Rate Swap [Member] | Subsequent Event [Member] |
|
|
|
|
|
|
| Debt Instrument [Line Items] |
|
|
|
|
|
|
| Secured credit facility, principal amount outstanding |
|
|
|
|
|
$ 150,000
|