Nature of operations and summary of significant accounting policies (Reorganization, Fresh Start Accounting and Comparability of Financial Statements to Prior Periods) (Details)	Mar. 21, 2017
Maximum
Fresh Start Adjustment
Fresh start voting share percentage of existing shareholders in emerging entity	50.00%

Fresh start adjustment voting share percentage of existing shareholders in emerging entity.

No definition available.

Name:	chap_FreshStartAdjustmentVotingSharePercentageOfExistingShareholdersInEmergingEntity
Namespace Prefix:	chap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant