Summary of significant accounting policies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013 property	Dec. 31, 2012	Dec. 31, 2011
Accounting Policies [Abstract]
Credit value adjustment, percentage of fair value of derivatives for Level 3 classification greater than	20.00%
Marketing costs	$ 40,612	$ 35,960	$ 36,413
Number of properties in Mexico for which local currency is not applicable	1

Expenditures for planning and executing the conception, pricing, promotion, and distribution of ideas, goods, and services. Costs of public relations and corporate promotions are typically considered to be marketing costs.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.4)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Name:	us-gaap_MarketingExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration