Stock-Based Compensation Performance Share Units Activity (Details) - 6 months ended Jun. 30, 2015 - PSU - $ / shares		Total
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, shares, beginning of period		43,219
Outstanding, weighted average fair value, beginning of period		$ 74.35
Granted, shares	[1]	65,982
Granted, weighted average fair value	[1]	$ 68.10
DividendEquivalentUnitsGranted		840
DividendEquivalentUnitsWeightedAverageFairValueGrants		$ 54.32
Adjustments due to the Special Cash Dividend	[1]	11,575
Outstanding and nonvested, shares, end of period	[1],[2]	121,616
Outstanding and nonvested, weighted average fair value, end of period	[1],[2]	$ 63.74
Adjustments due to the Special Cash Dividend - PSUs Not Deemed Granted	[1]	5,907

[1] Represents shares of PSUs for which performance targets have been established and which are deemed granted under U.S. GAAP.

[2] The weighted average fair value of outstanding PSUs as of June 30, 2015 reflects the adjustment for the Special Cash Dividend.