Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
PLUM CREEK TIMBER CO INC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 28
PLUM CREEK TIMBERLANDS L P [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Amortized Cost Basis	28
Categories of Investments, Marketable Securities, Trading Securities [Member] | PLUM CREEK TIMBER CO INC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Compensation Obligations Included in Other Liabilities	5	5
Categories of Investments, Marketable Securities, Trading Securities [Member] | PLUM CREEK TIMBERLANDS L P [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred Compensation Obligations Included in Other Liabilities	$ 5	$ 5