Lease Intangible Liabilities Net (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2012
Lease Intangible Liabilities, Net [Line Items]
Accumulated amortization of lease intangible liabilities	$ 5.4	$ 5.0
Weighted average remaining life of lease intangible liabilities (in months)	134 months	134 months

Lease intangible liabilities, weighted average useful life.

No definition available.

Name:	exl_LeaseIntangibleLiabilitiesWeightedAverageUsefulLife
Namespace Prefix:	exl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration