Incentive Plan (Tables)

6 Months Ended

Jun. 30, 2016

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of Long-Term Incentive Unit Activity

Below is a summary of our long-term incentive unit activity for the six months ended June 30, 2016.

Unvested Long-term Incentive Units	Units		Weighted-Average Grant Date Fair Value
Unvested, beginning of period	276,669		$	62.92
Granted	24,823		84.65
Vested	(134,318	)	62.74
Cancelled or expired	—		—
Unvested, end of period	167,174		$	66.28

Market Performance Based Awards

In the event that the RMS Relative Market Performance during the Market Performance Period is achieved at the “threshold,” “target” or “high” level as set forth below, the awards will become vested as to the market condition with respect to the percentage of Class D units or RSUs, as applicable, set forth below:

Level	RMS Relative Market Performance (2015 and 2016 Awards)	Market Performance Vesting Percentage
Below Threshold Level	< -300 basis points	0	%
Threshold Level	-300 basis points	25	%
Target Level	100 basis points	50	%
High Level	> 500 basis points	100	%

Summary of Incentive Award Plan's Stock Option

The following table summarizes the Amended and Restated 2004 Incentive Award Plan’s stock option activity for the six-month period ended June 30, 2016:

	Period Ended June 30, 2016
	Shares		Weighted average exercise price
Options outstanding, beginning of period	51,622		$	41.04
Exercised	(30,945	)	40.58
Options outstanding, end of period	20,677		$	41.73
Exercisable, end of period	20,677		$	41.73

Summary of Stock Options Outstanding and Exercisable

The following table summarizes information about stock options outstanding and exercisable as of June 30, 2016:

Options outstanding and exercisable
Exercise price	Number outstanding	Weighted-average remaining contractual  life (years)	Weighted-average exercise price		Aggregate intrinsic value
$41.73	20,677	0.84	$	41.73	$	1,390,735

Summary of Restricted Stock Activity

Below is a summary of our restricted stock activity for the six months ended June 30, 2016.

Unvested Restricted Stock	Shares		Weighted-Average Grant Date Fair Value
Unvested, beginning of period	271,339		$	61.37
Granted	136,566		80.96
Vested	(101,181	)	61.07
Cancelled or expired	(22,325	)	65.93
Unvested, end of period	284,399		$	70.54