| Report Element Information |
| Run date/time: 6/5/2011 7:34:40 AM |
| Report Element Attributes: |
| Report element from taxonomy prefix: | us-gaap |
| US GAAP taxonomy standard label: | us-gaap: Common Class A [Member] |
| Filer taxonomy standard label: | Common Class A [Member] |
| Documentation: | A classification of common stock. |
| Balance type: | |
| Period type: | For Period (duration) |
| Report element type: | [Member] |
| Data type: | [Member] (nonnum:domainItemType) |
| ID: | us-gaap_CommonClassAMember |
| Name: | us-gaap:CommonClassAMember |
| Labels of Report Element: (Labels from filer taxonomy, does not include other labels) |
| Role: | Label | Lang |
| Standard label (http://www.xbrl.org/2003/role/label) | Common Class A [Member] | en-US |
| References of Report Element, FASB Accounting Standards Codification: |
| Publisher, Name: | Topic | Sub Topic | Glossary | URI |
| References of Report Element, SEC Regulation S-X (SX): |
| Publisher, Name: | Number | Section | Paragraph | Subparagraph | Article |
| References of Report Element, US GAAP Legacy: |
| Publisher: | Name | Number | Chapter | Section | Paragraph | Subparagraph | Article | Clause | Appendix |