Leases: Lessee (Details)	3 Months Ended
Mar. 31, 2019
Minimum
Lessee, Lease, Description [Line Items]
Lessee - Lease Term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Lessee - Lease Term	37 years

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_LesseeLeaseDescriptionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration