Summary of Significant Accounting Policies - Supplemental disclosure of cash flow information (Details 11) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Noncash Investing Activities:
Accounts Payable Outstanding Related to Capital Additions	$ 14,935	[1]	$ 6,558	[1]

[1] Amounts are included in cash used for capital expenditures in subsequent periods when payables are settled.